Glossary

Shale

Fact Sheet:

Chemical Composition: Primarily composed of clay minerals (such as kaolinite, illite, and chlorite), quartz, feldspar, and organic matter
Hardness: 3 on the Mohs scale
Crystal System: Sedimentary rock, finely laminated, clastic
Color Varieties: Gray, black, brown, green, red, yellow
Major Localities: United States, Canada, China, Germany, Brazil, and the United Kingdom
Common Uses: Source of natural gas and oil (shale gas/oil), raw material for cement and bricks, and in geological research

Introduction: Shale is one of the most common sedimentary rocks on Earth, known for its fine-grained texture and its ability to break into thin ...

Limestone

Fact Sheet:

Chemical Composition: Primarily calcium carbonate (CaCO₃), typically in the form of calcite or aragonite
Hardness: 3 on the Mohs scale
Crystal System: Sedimentary rock (usually not crystalline in the same way as minerals, but made up of calcite crystals)
Color Varieties: White, gray, cream, yellow, and shades of brown
Major Localities: United States, China, India, Mexico, Brazil, and the United Kingdom
Common Uses: Building material, cement production, aggregate for roads, lime production, and in water treatment

Introduction: Limestone is one of the most common sedimentary rocks on Earth, forming the foundation of much of the ...

Scheelite

Fact Sheet:

Chemical Composition: Calcium tungstate (CaWO₄)
Hardness: 4.5 to 5 on the Mohs scale
Crystal System: Tetragonal
Color Varieties: Colorless, white, gray, yellow, orange, brown, green, and blue
Major Localities: China, United States, Austria, Bolivia, and Russia
Common Uses: Primary source of tungsten, used in industrial tools, steel alloys, light bulbs, and military applications

Introduction: Scheelite is a significant ore mineral for tungsten, one of the hardest and most heat-resistant metals on Earth. Tungsten, derived from scheelite, is essential for various industrial applications, including the production of high-strength alloys, cutting tools, and electrical components. First discovered ...

Sandstone

Fact Sheet:

Chemical Composition: Primarily composed of quartz (SiO₂) and feldspar, with minor amounts of other minerals like clay, calcite, and iron oxides
Hardness: 6 to 7 on the Mohs scale (depending on composition)
Crystal System: Sedimentary rock (clastic)
Color Varieties: Tan, brown, yellow, red, gray, pink, and white
Major Localities: United States, India, China, Australia, Egypt, and the United Kingdom
Common Uses: Construction material, decorative stone, paving, landscaping, and in glassmaking

Introduction: Sandstone is one of the most abundant and versatile sedimentary rocks on Earth, forming from the cementation of sand-sized grains of mineral, rock, or ...

Coal

Fact Sheet:

Chemical Composition: Primarily carbon, with varying amounts of hydrogen, sulfur, oxygen, and nitrogen
Hardness: 1 to 2 on the Mohs scale (varies by coal type)
Formation: Sedimentary rock formed from the accumulation and decomposition of organic matter, primarily plant material
Color Varieties: Black, brownish-black
Major Localities: United States, China, India, Australia, Russia, and South Africa
Common Uses: Electricity generation, steel production, cement manufacturing, and as a liquid fuel

Introduction: Coal is one of the world’s most important energy resources, playing a pivotal role in the development of modern industrial societies. Formed over millions of years ...

Quartzite

Fact Sheet:

Chemical Composition: Primarily composed of quartz (SiO₂)
Hardness: 7 on the Mohs scale
Crystal System: Metamorphic rock, non-foliated
Color Varieties: White, gray, pink, red, yellow, blue, green, and purple
Major Localities: United States, Brazil, Norway, South Africa, India, and Canada
Common Uses: Construction material, decorative stone, countertops, road ballast, and architectural applications

Introduction: Quartzite is a hard, durable metamorphic rock primarily composed of quartz that forms from the recrystallization of sandstone under intense heat and pressure. This process transforms the original quartz grains in the sandstone into a dense, interlocking mosaic of quartz crystals. Quartzite’s ...

Kernite

Fact Sheet:

Chemical Composition: Na₂B₄O₆(OH)₂·3H₂O (Hydrated Sodium Borate)
Hardness: 2.5 to 3 on the Mohs scale
Crystal System: Monoclinic
Color Varieties: Colorless, white, pale yellow, or gray
Major Localities: United States (California), Argentina, Turkey, and Russia
Common Uses: Source of boron, used in glassmaking, detergents, ceramics, and as an insecticide

Introduction: Kernite is an important borate mineral, mainly valued for its high boron content, which makes it a key raw material in various industrial applications. Discovered in Kern County, California, after which it is named, kernite is primarily mined for its use in producing boron compounds, essential ...

Amphibole

Fact Sheet:

Chemical Composition: A group of inosilicate minerals with a general formula (Ca, Na, K)₂–₃(Mg, Fe, Al)₅(Si, Al)₈O₂₂(OH, F)₂
Hardness: 5 to 6 on the Mohs scale
Crystal System: Monoclinic or orthorhombic
Color Varieties: Green, black, brown, yellow, blue
Major Localities: United States, Canada, Italy, Norway, and Japan
Common Uses: Geological research, asbestos (some forms), ornamental stone, and industrial materials

Introduction: Amphibole is a diverse group of minerals that includes several important rock-forming members. Known for their fibrous crystal habit and presence in both igneous and metamorphic rocks, amphiboles play a crucial role in understanding geological ...

Mica

Fact Sheet:
– Chemical Composition: A group of silicate minerals with varying compositions; common forms include muscovite (KAl₂(AlSi₃O₁₀)(OH)₂) and biotite (K(Mg,Fe)₃(AlSi₃O₁₀)(OH)₂)
– Hardness: 2.5 to 3 on the Mohs scale
– Crystal System: Monoclinic
– Color Varieties: Colorless, brown, green, yellow, purple, and black
– Major Localities: India, Russia, the United States, and Madagascar
– Common Uses: Insulation, cosmetics, paints, and electronics

Introduction: Mica is a versatile and widespread group of minerals known for their distinctive layered structure and excellent cleavage properties, which allow them to be split into thin, flexible sheets. These minerals play a crucial role in various ...

Schist

Fact Sheet:

Chemical Composition: Primarily composed of mica (muscovite, biotite), quartz, feldspar, and other minerals depending on the type (e.g., garnet, chlorite, talc)
Hardness: Varies depending on mineral composition, typically 3 to 5 on the Mohs scale
Crystal System: Metamorphic rock, foliated (layered)
Color Varieties: Gray, brown, black, silver, green, and sometimes reddish depending on mineral content
Major Localities: United States, Canada, Scotland, Switzerland, India, and Brazil
Common Uses: Construction material, decorative stone, gemstone source, and geological research

Introduction: Schist is a highly foliated, coarse-grained metamorphic rock known for its abundant platy or flaky minerals, particularly micas ...

Pyroxene

Fact Sheet:

Chemical Composition: General formula XY(Si, Al)₂O₆, where X can be calcium (Ca), sodium (Na), iron (Fe²⁺), or magnesium (Mg), and Y is typically magnesium (Mg), iron (Fe), or aluminum (Al)
Hardness: 5 to 7 on the Mohs scale
Crystal System: Monoclinic or orthorhombic
Color Varieties: Green, black, brown, white, yellow, and dark gray
Major Localities: United States, Italy, Norway, Australia, Canada, and Japan
Common Uses: Rock-forming mineral in igneous and metamorphic rocks, ceramics, and geological research

Introduction: Pyroxene is a group of important rock-forming minerals found in many igneous and metamorphic rocks. Characterized by their ...

Bauxite

Fact Sheet:
– Chemical Composition: A mixture of aluminum hydroxides, predominantly gibbsite (Al(OH)₃), boehmite (γ-AlO(OH)), and diaspore (α-AlO(OH))
– Hardness: 1 to 3 on the Mohs scale
– Crystal System: Amorphous (typically not crystalline)
– Color Varieties: White, gray, yellow, orange, red, brown
– Major Localities: Australia, Guinea, Brazil, and Jamaica
– Common Uses: Primary source of aluminum, refractory materials, abrasives, and in cement production

Introduction: Bauxite is the world’s primary source of aluminum, a metal critically important for modern life. This mineral was named after the village of Les Baux in southern France, where it was first discovered in ...

Beryl

Fact Sheet:

Chemical Composition: Be₃Al₂(SiO₃)₆ (Beryllium Aluminum Silicate)
Hardness: 7.5 to 8 on the Mohs scale
Crystal System: Hexagonal
Color Varieties: Green (emerald), blue (aquamarine), yellow (heliodor), pink (morganite), colorless (goshenite), red (red beryl)
Major Localities: Brazil, Colombia, Madagascar, Russia, the United States, and Pakistan
Common Uses: Gemstones (emerald, aquamarine), source of beryllium, and in industrial applications

Introduction: Beryl is a fascinating mineral known for its wide range of beautiful gemstone varieties, including emerald and aquamarine. This mineral has been prized throughout history for its stunning colors and crystal clarity, making it one of the most sought-after ...

Biotite

Fact Sheet:
– Chemical Composition: K(Mg,Fe)₃(AlSi₃O₁₀)(F,OH)₂
– Hardness: 2.5 to 3 on the Mohs scale
– Crystal System: Monoclinic
– Color Varieties: Black, dark brown, dark green
– Major Localities: Russia, Canada, the United States, and Brazil
– Common Uses: Electrical insulator, soil additive, petrologic study

Introduction: Biotite is a common phyllosilicate mineral within the mica group, characterized by its dark coloration and sheet-like crystal structure. It is named after the French physicist Jean-Baptiste Biot, who made significant contributions to the study of the optical properties of mica.

Formation: Biotite forms in a variety of geological environments, including igneous, metamorphic, ...

Olivine

Fact Sheet:
– Chemical Composition: (Mg, Fe)₂SiO₄ (Magnesium Iron Silicate)
– Hardness: 6.5 to 7 on the Mohs scale
– Crystal System: Orthorhombic
– Color Varieties: Green, yellow-green, brown
– Major Localities: United States, Norway, Myanmar, and Pakistan
– Common Uses: Gemstone (peridot), refractory material, industrial sand, and in high-temperature furnaces

Introduction: Olivine, known for its beautiful green hue, is a common silicate mineral that forms deep within the Earth’s mantle. It is best known as the gemstone peridot and has significant geological importance due to its presence in mantle rocks and its role in tectonic processes.

Formation: Olivine primarily ...

Barite

Fact Sheet:

Chemical Composition: BaSO₄ (Barium Sulfate)
Hardness: 3 to 3.5 on the Mohs scale
Crystal System: Orthorhombic
Color Varieties: Colorless, white, yellow, brown, blue, green, red
Major Localities: China, India, Morocco, United States, and Turkey
Common Uses: Drilling mud, paints, radiation shielding, and as a filler in rubber and plastics

Introduction: Barite, also known as baryte, is a dense mineral primarily composed of barium sulfate. Its name comes from the Greek word “barys,” meaning heavy, due to its exceptional density. Barite has numerous industrial applications, particularly in oil and gas drilling, where it is used to ...

Monazite

Fact Sheet:

Chemical Composition: (Ce, La, Nd, Th)PO₄ (Phosphate of rare earth elements like cerium, lanthanum, neodymium, and thorium)
Hardness: 5 to 5.5 on the Mohs scale
Crystal System: Monoclinic
Color Varieties: Reddish-brown, yellow, green, gray, and white
Major Localities: India, Brazil, Australia, United States, Madagascar, and South Africa
Common Uses: Source of rare earth elements (REEs), thorium, used in electronics, magnets, and nuclear energy

Introduction: Monazite is a phosphate mineral that is an important source of rare earth elements (REEs) such as cerium, lanthanum, and neodymium, as well as thorium, a radioactive element used in nuclear ...

Granite

Fact Sheet:

Chemical Composition: Primarily composed of quartz, feldspar (orthoclase and plagioclase), and mica (biotite or muscovite)
Hardness: 6 to 7 on the Mohs scale
Crystal System: Igneous, phaneritic (coarse-grained)
Color Varieties: Pink, red, gray, white, black, and combinations thereof
Major Localities: Brazil, India, China, the United States, Canada, and South Africa
Common Uses: Countertops, construction materials, monuments, sculptures, and decorative stone

Introduction: Granite is one of the most common and widely used igneous rocks on Earth. Known for its durability, coarse grain, and wide range of colors, granite has played a crucial role in construction, architecture, ...

Chlorite

Fact Sheet:
– Chemical Composition: (Mg,Fe,Li)₅Al(Si₃Al)O₁₀(OH)₈ (variable composition with magnesium, iron, and aluminum)
– Hardness: 2 to 2.5 on the Mohs scale
– Crystal System: Monoclinic
– Color Varieties: Green, white, yellow, pink, black
– Major Localities: United States, Canada, Russia, and Italy
– Common Uses: Indicator of metamorphic conditions, industrial filler, additive in paints and plastics

Introduction: Chlorite is a group of common phyllosilicate minerals that form during the metamorphism of other minerals. Its name is derived from the Greek word “chloros,” meaning green, due to its typical color. Chlorite plays a significant role in geology as an indicator ...

Galena

Fact Sheet:

Chemical Composition: PbS (Lead Sulfide)
Hardness: 2.5 on the Mohs scale
Crystal System: Cubic
Color Varieties: Lead-gray, silver-gray
Major Localities: United States, Mexico, Germany, Australia, Peru, and the UK
Common Uses: Primary ore of lead, source of silver, industrial materials, lead-acid batteries, and radiation shielding

Introduction: Galena is the most important lead ore and one of the most abundant and widely distributed sulfide minerals. Its distinctive metallic luster and high density make it easy to identify, and its cubic crystal form is iconic. Beyond its significance as a lead ore, galena is also a major ...

Muscovite

Fact Sheet:
– Chemical Composition: KAl₂(AlSi₃O₁₀)(F,OH)₂
– Hardness: 2 to 2.5 on the Mohs scale
– Crystal System: Monoclinic
– Color Varieties: Colorless, white, silver, yellow, brown, green
– Major Localities: Russia, India, Brazil, and the United States
– Common Uses: Electrical insulator, fireproofing materials, cosmetics, and as a gemstone

Introduction: Muscovite, a member of the mica group, is a common phyllosilicate mineral known for its brilliant cleavage and lustrous appearance. Named after the Muscovy region in Russia, where it was historically mined, muscovite is used in a variety of industrial and decorative applications.

Formation: Muscovite forms in igneous, metamorphic, ...

Gypsum

Fact Sheet:
– Chemical Composition: CaSO₄·2H₂O (Calcium Sulfate Dihydrate)
– Hardness: 2 on the Mohs scale
– Crystal System: Monoclinic
– Color Varieties: White, colorless, gray, yellow, red, brown
– Major Localities: United States, China, Iran, and Spain
– Common Uses: Construction material (plaster and drywall), agricultural soil conditioner, cement additive, and sculpting medium

Introduction: Gypsum, a soft sulfate mineral composed of calcium sulfate dihydrate, is widely used in construction and agriculture. Its name originates from the Greek word “gypsos,” meaning plaster. Gypsum’s versatility and abundance make it a critical mineral in various industrial applications, from building homes to improving ...

Basalt

Fact Sheet:

Chemical Composition: Primarily composed of plagioclase feldspar, pyroxene, and olivine (low in silica, rich in iron and magnesium)
Hardness: 6 on the Mohs scale
Crystal System: Basalt is a fine-grained igneous rock, typically displaying an aphanitic texture
Color Varieties: Dark gray, black, greenish-black, brown
Major Localities: Iceland, Hawaii (USA), India, Russia, and the Pacific Ocean floor
Common Uses: Construction (aggregate, road base), monuments, insulation, and as a component of volcanic activity research

Introduction: Basalt is the most common extrusive igneous rock on Earth, covering more than 70% of the planet’s surface. Formed through the rapid ...

Calcite

Fact Sheet:
– Chemical Composition: CaCO₃ (Calcium Carbonate)
– Hardness: 3 on the Mohs scale
– Crystal System: Trigonal
– Color Varieties: Colorless, white, pink, green, blue, yellow, and brown
– Major Localities: Mexico, Iceland, Germany, and the United States
– Common Uses: Construction material, agricultural soil treatment, and in the production of cement and lime

Introduction: Calcite is a ubiquitous mineral, present in substantial portions of the Earth’s crust and a primary component of limestone and marble. Its broad distribution and diverse applications make it a mineral of significant geological and economic importance.

Formation: Calcite forms in both sedimentary ...

Talc

Fact Sheet:
– Chemical Composition: Mg₃Si₄O₁₀(OH)₂ (Magnesium Silicate Hydroxide)
– Hardness: 1 on the Mohs scale
– Crystal System: Monoclinic or triclinic
– Color Varieties: White, gray, green, brown, colorless
– Major Localities: United States, China, Brazil, India, and France
– Common Uses: Baby powder, cosmetics, ceramics, paint, paper, and plastics

Introduction: Talc is the softest mineral known, ranking as 1 on the Mohs hardness scale. Its ability to be easily scratched by a fingernail and its greasy feel make it unique among minerals. Talc has been used by humans for millennia in various applications, from personal care products to ...

Wulfenite

Fact Sheet:

Chemical Composition: PbMoO₄ (lead molybdate)
Hardness: 2.5 to 3 on the Mohs scale
Crystal System: Tetragonal
Color Varieties: Orange, yellow, red, brown, and sometimes colorless
Major Localities: Mexico, United States, Morocco, Namibia, and Austria
Common Uses: Ore of molybdenum, collector’s mineral, and gemstone

Introduction: Wulfenite is a lead molybdate mineral that is prized for its vivid colors, most commonly ranging from bright orange to yellow, red, and even brown. Its striking, often perfectly formed tabular crystals make wulfenite highly sought after by mineral collectors. The mineral is named after Austrian mineralogist Franz Xavier von Wulfen, ...

Garnet

Fact Sheet:
– Chemical Composition: A group of silicate minerals with the general formula X₃Y₂(SiO₄)₃, where X can be Ca, Mg, Fe, or Mn, and Y can be Al, Fe, or Cr
– Hardness: 6.5 to 7.5 on the Mohs scale
– Crystal System: Isometric
– Color Varieties: Red, green, yellow, orange, brown, purple, pink, black
– Major Localities: India, Madagascar, Sri Lanka, the United States, and Russia
– Common Uses: Gemstones, abrasives, industrial applications

Introduction: Garnet is a diverse and widespread group of silicate minerals prized for its rich array of colors and durability. Known since ancient times, garnets ...

Descloizite

Fact Sheet:

Chemical Composition: PbZnVO₄(OH) (Lead Zinc Vanadate Hydroxide)
Hardness: 3 to 3.5 on the Mohs scale
Crystal System: Orthorhombic
Color Varieties: Brown, red, black, yellow, green
Major Localities: Namibia, Mexico, South Africa, Austria, and the United States
Common Uses: Source of vanadium, mineral collections

Introduction: Descloizite is a rare lead-zinc vanadate mineral, highly prized by collectors for its bright colors and well-formed crystals. Named after the French mineralogist Alfred Des Cloizeaux, this mineral is known for its striking appearance and its role as a minor ore of vanadium. Descloizite is typically found in the oxidized zones ...

Rhyolite

Fact Sheet:

Chemical Composition: High in silica (SiO₂) with feldspar, quartz, and biotite or amphibole
Hardness: 6 on the Mohs scale
Crystal System: Extrusive igneous rock (volcanic), fine-grained (aphanitic)
Color Varieties: Gray, pink, light brown, and reddish shades
Major Localities: United States, Iceland, New Zealand, Germany, and Turkey
Common Uses: Decorative stone, construction material, aggregate, and in geological research

Introduction: Rhyolite is a fine-grained, felsic (silica-rich) volcanic rock that is the extrusive equivalent of granite. It forms from the rapid cooling of high-silica magma at or near the Earth’s surface, often during explosive volcanic eruptions. Rhyolite’s light ...

Marble

Fact Sheet:

Chemical Composition: Primarily composed of calcium carbonate (CaCO₃) in the form of calcite or dolomite
Hardness: 3 to 5 on the Mohs scale (depending on composition)
Crystal System: Metamorphic rock, non-foliated
Color Varieties: White, pink, green, black, gray, brown, red, blue, and multicolored
Major Localities: Italy, Greece, India, Turkey, China, and the United States
Common Uses: Sculpture, architecture, flooring, countertops, and decorative stone

Introduction: Marble is one of the most beautiful and revered stones in human history, prized for its aesthetic appeal, durability, and workability. It is a metamorphic rock formed from the recrystallization of ...

Magnetite

Fact Sheet:
– Chemical Composition: Fe₃O₄ (Iron(II,III) Oxide)
– Hardness: 5.5 to 6.5 on the Mohs scale
– Crystal System: Isometric
– Color Varieties: Black to brownish-black with a metallic luster
– Major Localities: Australia, Brazil, Canada, and the United States
– Common Uses: Iron ore, magnetic materials, and catalysts

Introduction: Magnetite is a fascinating mineral known for its strong magnetic properties, which are unique among naturally occurring minerals. Its name comes from Magnesia, a region in Greece where the mineral was first discovered. Beyond its magnetic allure, magnetite is a crucial iron ore and has various industrial applications.

Formation: ...

Zircon

Fact Sheet:
– Chemical Composition: ZrSiO₄ (Zirconium Silicate)
– Hardness: 7.5 on the Mohs scale
– Crystal System: Tetragonal
– Color Varieties: Colorless, yellow, red, brown, green, blue
– Major Localities: Australia, Sri Lanka, Brazil, Russia, and the United States
– Common Uses: Gemstones, geochronology, ceramics, and refractory materials

Introduction: Zircon is a remarkable mineral known for its brilliant luster, diverse color range, and significant role in geological studies. Often used as a gemstone, zircon is also a vital tool for scientists studying the Earth’s history, as it can contain traces of uranium and thorium, making it useful for radiometric ...

Adamite

Fact Sheet:

Chemical Composition: Zn₂(AsO₄)(OH) (Zinc Arsenate Hydroxide)
Hardness: 3.5 on the Mohs scale
Crystal System: Orthorhombic
Color Varieties: Yellow, green, purple, pink, blue
Major Localities: Mexico, Greece, Namibia, and Chile-
Common Uses: Mineral collections, geological research, occasionally used in jewelry

Introduction: Adamite is a rare and radiant mineral, known for its bright colors, most commonly yellow and green, and its beautiful, lustrous crystals. It often forms in the oxidation zones of zinc and arsenic-rich deposits and is sought after by mineral collectors for its aesthetic appeal.

Formation: Adamite forms as a secondary mineral in the oxidation ...

Fluorite

Fact Sheet:
– Chemical Composition: CaF₂ (Calcium Fluoride)
– Hardness: 4 on the Mohs scale
– Crystal System: Isometric
– Color Varieties: Colorless, purple, blue, green, yellow, pink, red, and black
– Major Localities: China, Mexico, South Africa, and the United States
– Common Uses: Flux in steelmaking, glass and ceramics production, hydrofluoric acid production, and as a gemstone

Introduction: Fluorite, also known as fluorspar, is a stunning mineral prized for its vibrant range of colors and its importance in industrial applications. Its name comes from the Latin word “fluere,” meaning “to flow,” due to its use as a flux ...

Vanadinite

Fact Sheet:

Chemical Composition: Pb₅(VO₄)₃Cl (lead chlorovanadate)
Hardness: 3 to 4 on the Mohs scale
Crystal System: Hexagonal
Color Varieties: Red, orange, brown, yellow, and rarely colorless
Major Localities: Morocco, United States, Mexico, Namibia, and South Africa
Common Uses: Primary source of vanadium, lead ore, and a popular collector’s mineral

Introduction: Vanadinite is a vibrant red to orange mineral, best known for its striking crystal formations and its role as an important ore of vanadium and lead. It belongs to the apatite group of minerals and forms hexagonal crystals that are often found in the oxidized zones ...

Pyrite

Fact Sheet:
– Chemical Composition: FeS₂ (Iron Disulfide)
– Hardness: 6 to 6.5 on the Mohs scale
– Crystal System: Isometric
– Color Varieties: Brass-yellow with a metallic luster, often tarnishing to brown
– Major Localities: Spain, Peru, Italy, and the United States
– Common Uses: Sulfur extraction, iron production, and as a gemstone

Introduction: Pyrite, commonly known as “Fool’s Gold” due to its striking resemblance to gold, is a widespread and intriguing mineral. Its name derives from the Greek word “pyr,” meaning fire, as pyrite can create sparks when struck against steel. Despite its deceptive appearance, pyrite holds significant ...

Hematite

Fact Sheet:
– Chemical Composition: Fe₂O₃ (Iron(III) Oxide)
– Hardness: 5.5 to 6.5 on the Mohs scale
– Crystal System: Trigonal
– Color Varieties: Metallic gray, black, red to reddish-brown
– Major Localities: Brazil, Australia, China, and the United States
– Common Uses: Iron ore, pigment, radiation shielding, and jewelry

Introduction: Hematite, renowned for its striking metallic luster and deep red streak, is a major ore of iron and a significant industrial mineral. Its name derives from the Greek word “haima,” meaning blood, due to the red coloration it imparts when powdered. Hematite has been utilized by humans for thousands ...

Scorodite

Fact Sheet:

Chemical Composition: FeAsO₄·2H₂O (hydrated iron arsenate)
Hardness: 3.5 to 4 on the Mohs scale
Crystal System: Orthorhombic
Color Varieties: Blue, green, gray, yellow, brown, and colorless
Major Localities: Germany, United States, Canada, Namibia, Mexico, and Czech Republic
Common Uses: Source of arsenic, collector’s mineral, and in environmental studies for arsenic containment

Introduction: Scorodite is a secondary mineral that forms from the oxidation of arsenic-rich minerals such as arsenopyrite. It is a hydrated iron arsenate, known for its beautiful crystals and striking colors, typically blue or green. Though scorodite is prized by mineral collectors for its ...

Gneiss

Fact Sheet:

Chemical Composition: Variable; primarily composed of feldspar, quartz, and mica, with minor amounts of other minerals such as amphibole and garnet
Hardness: 6 to 7 on the Mohs scale
Crystal System: Metamorphic rock (not crystalline in the same way as minerals)
Color Varieties: Banded or foliated, typically gray, pink, white, and black, with alternating light and dark mineral layers
Major Localities: United States, Canada, Norway, Scotland, India, and South Africa
Common Uses: Building material, decorative stone, aggregate for roads, and landscaping

Introduction: Gneiss (pronounced “nice”) is one of the most common metamorphic rocks in the ...

Feldspar

Fact Sheet:
– Chemical Composition: A group of aluminum silicates containing potassium, sodium, or calcium (KAlSi₃O₈ – NaAlSi₃O₈ – CaAl₂Si₂O₈)
– Hardness: 6-6.5 on the Mohs scale
– Crystal System: Monoclinic and triclinic
– Color Varieties: Typically opaque in white, pink, gray, or brown tones
– Major Localities: Italy, Turkey, the United States, and India
– Common Uses: Ceramics, glass production, and as decorative stones in construction

Introduction: Feldspar is the most abundant mineral group found in the Earth’s crust. Representing more than 40% of its composition, these minerals are indispensable in both geological and industrial applications.

Formation: Feldspars are ...

Borax

Fact Sheet:

Chemical Composition: Na₂[B₄O₅(OH)₄]·8H₂O (Sodium Borate Decahydrate)
Hardness: 2 to 2.5 on the Mohs scale
Crystal System: Monoclinic
Color Varieties: Colorless to white, sometimes with gray, yellow, green, or brown tints due to impurities
Major Localities: United States (California), Turkey, Chile, and Tibet
Common Uses: Cleaning agent, glassmaking, ceramics, metallurgy, and as an insecticide

Introduction: Borax is a versatile mineral widely known for its use in household cleaning products, but its industrial and scientific importance goes far beyond that. A naturally occurring compound of boron, sodium, and water, borax plays a crucial role in glassmaking, agriculture, ...

Apatite

Fact Sheet:

Chemical Composition: Ca₅(PO₄)₃(F, Cl, OH) (Calcium Phosphate)
Hardness: 5 on the Mohs scale
Crystal System: Hexagonal
Color Varieties: Green, blue, yellow, purple, brown, pink, and colorless
Major Localities: Canada, Brazil, Russia, Mexico, and the United States
Common Uses: Source of phosphate for fertilizer, gemstones, and industrial applications

Introduction: Apatite is a widely occurring mineral, essential for both biological processes and industrial applications. Its name is derived from the Greek word “apate,” meaning “deceit,” due to its similarity to other minerals, which led to confusion in its early identification. Apatite is the primary source of phosphorus, ...

Dolomite

Fact Sheet:
– Chemical Composition: CaMg(CO₃)₂ (Calcium Magnesium Carbonate)
– Hardness: 3.5 to 4 on the Mohs scale
– Crystal System: Trigonal
– Color Varieties: Typically colorless, white, gray, pink, or brown
– Major Localities: Italy, Switzerland, parts of the USA, and Canada
– Common Uses: Aggregate in construction, source of magnesium and lime, decorative stone, and refractory material

Introduction: Dolomite, also known as dolostone when in rock form, is a significant carbonate mineral that complements the Earth’s calcite-rich landscapes. It plays a pivotal role in sedimentary rock formations and has various industrial and environmental applications.

Formation: Dolomite forms through ...

Halite

Fact Sheet:
– Chemical Composition: NaCl (Sodium Chloride)
– Hardness: 2 to 2.5 on the Mohs scale
– Crystal System: Isometric
– Color Varieties: Colorless, white, blue, purple, pink, red, orange, yellow
– Major Localities: United States, China, Germany, Canada, and Poland
– Common Uses: Food seasoning, de-icing roads, chemical feedstock, water conditioning, and industrial applications

Introduction: Halite, commonly known as rock salt, is a mineral form of sodium chloride. It has been an essential resource for humans for thousands of years, used in everything from food preservation to modern industrial processes. The name “halite” is derived from the Greek ...

Diorite

Fact Sheet:

Chemical Composition: Intermediate igneous rock composed mainly of plagioclase feldspar (typically andesine) with biotite, hornblende, and/or pyroxene
Hardness: 6 to 7 on the Mohs scale
Crystal System: Igneous, coarse-grained (phaneritic)
Color Varieties: Gray to dark gray, speckled with black and white
Major Localities: United States, Germany, Scotland, Peru, and New Zealand
Common Uses: Construction material, dimension stone, historical monuments, and art

Introduction: Diorite is a durable, coarse-grained intrusive igneous rock known for its distinctive “salt-and-pepper” appearance, resulting from the intermingling of light-colored feldspar and dark minerals like biotite and hornblende. Diorite is chemically and mineralogically ...

Quartz

Fact Sheet:
– Chemical Composition: SiO₂ (Silicon Dioxide)
– Hardness: 7 on the Mohs scale
– Crystal System: Hexagonal
– Color Varieties: Clear, white, pink (rose quartz), black (smoky quartz), purple (amethyst), yellow (citrine), and others
– Major Localities: Brazil, Madagascar, the United States, and the Alps in Europe
Common Uses: Jewelry, electronic components, and as a decorative stone in construction

Introduction: Quartz, one of the most abundant minerals on the Earth’s surface, forms a key component of continental crust. Known for its durability and wide range of colors, quartz serves both aesthetic and functional purposes, making it a cornerstone ...

Tourmaline

Fact Sheet:

Chemical Composition: Complex boron silicate (variable formula: XY₃Z₆(T₆O₁₈)(BO₃)₃V₃W) where X = Ca, Na, K; Y = Al, Fe²⁺, Mg, Li, Mn²⁺; Z = Al, Mg, Cr, Fe³⁺; T = Si, Al; V = O, OH; W = OH, F, O
Hardness: 7 to 7.5 on the Mohs scale
Crystal System: Trigonal (hexagonal prisms)
Color Varieties: Black, green, pink, red, blue, yellow, brown, colorless, and multicolored
Major Localities: Brazil, Afghanistan, Pakistan, United States, Madagascar, and Namibia
Common Uses: Gemstone, collector’s mineral, piezoelectric applications, and decorative purposes

Introduction: Tourmaline is a strikingly colorful and complex boron silicate ...

^AAbyssal Plain

Abyssal plains are large, flat, and nearly featureless regions of the deep ocean floor, located at depths between 3,000 to 6,000 meters. These plains are formed through the slow accumulation of fine sediments, including clay and microscopic organisms, that descend from the ocean surface. The creation of abyssal plains is also influenced by the spreading of oceanic plates, which produces new seafloor. These regions are critical to understanding deep-sea sedimentation processes and the geological history of the ocean basins.

Reference: Craig R. Smith; Fabio C. De Leo; Angelo F. Bernardino; Andrew K. Sweetman; Pedro Martinez Arbizu (2008). “Abyssal food limitation, ecosystem structure and climate change”

^AAccretion

In geology, accretion refers to the process by which material is added to a tectonic plate at convergent boundaries. This material can include sediment, volcanic arcs, and other fragments of crust that are scraped off a subducting plate and attached to the overriding plate, forming an accretionary wedge. Accretion plays a significant role in the growth of continental crust and the formation of mountain ranges.

Reference: Ballard, Robert D. (1988). Exploring our living planet. National Geographic Book Service., National Geographic Society (U.S.) (Rev. ed.). Washington, D.C.: National Geographic Society. ISBN 0-87044-760-2. OCLC 18325626

^AAccretionary Wedge

An accretionary wedge is a large, wedge-shaped mass of sediment and oceanic crust that accumulates at convergent plate boundaries, where one plate is subducted beneath another. The sediments are scraped off the subducting plate and piled onto the overriding plate, forming complex structures of folded and faulted rocks. Accretionary wedges are key in understanding the tectonic evolution of convergent margins and the processes involved in mountain building.

Reference: https://www.usgs.gov/media/images/accretionary-wedge.

^AActive Margin

An active margin is a type of continental margin that is tectonically active, typically characterized by the presence of a convergent plate boundary where an oceanic plate is being subducted beneath a continental plate. Active margins are associated with features such as deep ocean trenches, volcanic arcs, and high seismic activity. They contrast with passive margins, which are tectonically inactive.

Reference: Orme, A. R. “1.10 Tectonism, Climate, and Geomorphology.” Treatise on Geomorphology 1 (2013): 146.

^AAeolian Dune

Description: Aeolian dunes are hills or ridges of sand formed by the wind in desert or coastal environments. The shape and size of aeolian dunes are influenced by wind direction, sand supply, and vegetation. These dunes are significant in the study of sedimentary processes and desert geomorphology, as well as in understanding past climatic conditions.

Reference: https://www.nps.gov/subjects/geology/aeolian-landforms.htm

^AAeolian Processes

Aeolian processes involve the erosion, transport, and deposition of sediments by wind. These processes are most effective in arid environments, where vegetation is sparse, and sediment is loose and dry. Aeolian features include dunes, loess deposits, and desert pavements. Understanding aeolian processes is important for interpreting past climate conditions and predicting future landscape changes in desert regions.

Reference: Lancaster, N. (1995). “Geomorphology of Desert Dunes.” Routledge.

^AAeolianite

Aeolianite is a type of sedimentary rock formed from the lithification of wind-blown (aeolian) sands. These rocks are typically composed of quartz grains and are found in coastal and desert environments. Aeolianites are important indicators of past climatic conditions and wind regimes and are studied to understand sedimentary processes in arid regions.

Reference: Brooke, B. (2001). “The Distribution and Formation of Coastal Aeolianite.” Earth-Science Reviews, 55(1-2), 135-164.

^AAgglomerate

Agglomerate is a coarse, volcanic rock composed of angular fragments of volcanic material that have been welded or cemented together. It forms from explosive volcanic eruptions and is typically found in volcanic settings, such as around vent areas. Agglomerates are important for understanding the eruptive history and dynamics of volcanoes.

Reference: Williams, H., & McBirney, A. R. (1979). Volcanology. Freeman, Cooper & Company.

^AAlbedo

Albedo is a measure of the reflectivity of a surface, expressed as the ratio of reflected radiation from the surface to the incident radiation upon it. In geology, albedo is important in studying Earth’s climate, as surfaces with high albedo (such as ice and snow) reflect most of the solar energy, while those with low albedo (such as forests and oceans) absorb more energy. Albedo effects are crucial in understanding climate change and energy balance on Earth.

Reference: Trenberth, K. E., & Fasullo, J. T. (2010). “Earth’s Global Energy Budget.” Bulletin of the American Meteorological Society, 91(3), 311-324.

^AAleutian Arc

The Aleutian Arc is a volcanic arc located in the northern Pacific Ocean, extending from Alaska to Russia. It is formed by the subduction of the Pacific Plate beneath the North American Plate, creating a chain of active volcanoes. The Aleutian Arc is a prime example of an island arc system and is significant for studying subduction-related volcanic activity, plate tectonics, and associated seismic hazards.

Reference: https://www.usgs.gov/publications/geologic-framework-aleutian-arc-alaska.

^AAlkaline Igneous Rock

Alkaline igneous rocks are a category of igneous rocks that contain higher concentrations of alkali metals (sodium and potassium) relative to silica. These rocks often form in tectonic settings such as continental rifts or hotspots. Examples include nepheline syenite and phonolite. Alkaline rocks are important for understanding mantle processes and the evolution of magmas in extensional tectonic environments.

Reference: https://www.sciencedirect.com/topics/earth-and-planetary-sciences/alkaline-rock

^AAllochthonous

The term allochthonous refers to rocks or sediments that have been transported from their place of origin and deposited in a different location, typically by tectonic forces. In geology, allochthonous units are often contrasted with autochthonous units, which have remained in their place of formation. Allochthonous materials provide insights into the dynamics of tectonic processes, such as thrust faulting and subduction.

Reference: Davis, G. H., & Reynolds, S. J. (1996). Structural Geology of Rocks and Regions. John Wiley & Sons.

^AAlluvial Fan

An alluvial fan is a triangular or fan-shaped deposit of gravel, sand, and smaller materials, created where a fast-flowing stream flattens out. Typically found at the base of mountain ranges, alluvial fans form when a stream’s gradient decreases, leading to sediment deposition. They are common in arid and semi-arid regions and are significant in interpreting past climatic and geological conditions, as well as in groundwater studies due to their porous nature.

Reference: Blair, T. C., & McPherson, J. G. (1994). “Alluvial Fans and Their Natural Distinction from Rivers Based on Morphology, Hydraulic Processes, Sedimentary Processes, and Facies Assemblages.” Journal of Sedimentary Research, 64(3), 450-489.

^AAmmonite

Ammonites are an extinct group of marine mollusk animals that existed from the Devonian to the Cretaceous period. Their spiral shells are commonly found as fossils and are used as index fossils to date the age of the rock layers in which they are found. Ammonites are important in paleontology for understanding the evolution of marine life and the environmental conditions of ancient oceans.

Reference: Monks, N., & Palmer, P. (2002). Ammonites. Smithsonian Books.

^AAmphitheater Valley

An amphitheater valley is a steep-walled, U-shaped valley that resembles an amphitheater in shape, often formed by the headward erosion of streams or glaciers. These valleys are common in mountainous regions and provide important insights into the processes of erosion, weathering, and the geomorphological evolution of landscapes.

Reference: Thornbury, W. D. (1965). Regional Geomorphology of the United States. John Wiley & Sons.

^AAnabranch

An anabranch is a section of a river or stream that diverts from the main channel and rejoins it downstream. Anabranches are common in river systems with low gradients and are often associated with braided rivers. The formation and evolution of anabranches are important for understanding river dynamics, sediment transport, and floodplain development.

Reference: Brierley, G. J., & Fryirs, K. A. (2005). Geomorphology and River Management: Applications of the River Styles Framework. Blackwell Publishing.

^AAnaerobic Environment

An anaerobic environment is one that lacks oxygen, which can significantly affect the types of chemical reactions that occur, as well as the types of organisms that can survive. In geology, anaerobic conditions are often found in deep sediments, swamps, and some groundwater systems. These environments are important in the study of biogeochemical cycles, particularly the formation of organic-rich sediments and fossil fuels.

Reference: Berner, R. A. (1981). “A New Geochemical Classification of Sedimentary Environments.” Journal of Sedimentary Research, 51(2), 359-365.

^AAnomalous Magnetic Field

An anomalous magnetic field refers to deviations in Earth’s magnetic field from the expected normal pattern. These anomalies can be caused by variations in the Earth’s crust, such as the presence of different types of rocks, or by external factors like solar wind. Studying these anomalies helps geophysicists understand the structure of the Earth’s crust and mantle, as well as past movements of tectonic plates.

Reference: Dyment, J., & Arkani-Hamed, J. (1998). “Geophysical Interpretation of Anomalous Magnetic Fields.” Geophysical Journal International, 133(2), 435-456.

^AAnthracite

Anthracite is the highest grade of coal, known for its high carbon content, low impurities, and high energy density. It is formed under conditions of high temperature and pressure, typically in geologically older formations. Anthracite is an important fuel source and has been extensively mined for its energy-rich properties, particularly in regions with significant industrial history.

Reference: Speight, J. G. (2012). The Chemistry and Technology of Coal. CRC Press.

^AAnthropocene

The Anthropocene is a proposed geological epoch that denotes the current period in Earth’s history, characterized by the significant impact of human activities on the planet’s geology and ecosystems. The term emphasizes the pervasive influence of humans on climate, biodiversity, and natural processes, potentially leaving a distinct stratigraphic signature in the rock record. The formal recognition of the Anthropocene is still under scientific debate.

Reference: Crutzen, P. J. (2006). “The Anthropocene.” In Earth System Science in the Anthropocene (pp. 13-18). Springer.

^AAnticline

An anticline is a type of fold in sedimentary strata that is arch-like in shape, with its oldest rocks located at the core of the fold. The limbs of an anticline dip away from the center, creating a convex-upward structure. Anticlines are important in petroleum geology because they can serve as traps for oil and natural gas, accumulating hydrocarbons in the crest of the fold.

Reference: Twiss, R. J., & Moores, E. M. (2007). Structural Geology. W.H. Freeman and Company.

^AAnticlinorium

An anticlinorium is a large-scale anticline or a series of anticlinal folds that together form a complex, mountainous structure. These structures are common in regions that have undergone significant compressional tectonic forces, such as during the formation of mountain ranges. The study of anticlinoria is important in understanding the large-scale tectonic evolution of orogenic belts.

Reference: Davis, G. H., & Reynolds, S. J. (1996). Structural Geology of Rocks and Regions. John Wiley & Sons.

^AAntiform

An antiform is a fold that has the shape of an arch, but unlike an anticline, it does not necessarily have the oldest rocks at its core. The term is used when the age relationships between the strata are unknown or irrelevant. Antiforms are important in the study of fold structures and tectonic deformation, providing information on the stresses and forces that have shaped a region’s geology.

Reference: Ramsay, J. G. (1967). Folding and Fracturing of Rocks. McGraw-Hill.

^NArchives: Glossary

Nappe fold structure refers to the large-scale folds associated with the formation of nappes during compressional tectonics. These structures are key features in understanding the deformation processes involved in orogeny and the tectonic evolution of mountain belts.

Reference: Ramsay, J. G., & Huber, M. I. (1987). “The Techniques of Modern Structural Geology, Volume 2: Folds and Fractures.” Academic Press.