The mineral composition of sands and sandstone can be very different and complex depending on the parent rocks, nature of weathering and erosion, transfer, and deposition. The clasts that makeup sand residue and sandstone include mineral grains and rock fragments of siliciclastic and carbonate composition, as well as fossil remains of the ...Mineral Deposits Studies Group · Near Surface Geophysics Group · Quaternary ... Flint is a microcrystalline rock made of silica and is considered to have begun ...Dolomite is a common rock-forming mineral. It is a calcium magnesium carbonate with a chemical composition of CaMg (CO 3) 2. It is the primary component of the sedimentary rock known as dolostone and the metamorphic rock known as dolomitic marble. Limestone that contains some dolomite is known as dolomitic limestone.1 Properties 1.1 Physical Properties 1.1.1 Hardness 1 1.1.2 Grain Size Very fine-grained 1.1.3 Fracture Not Available 1.1.4 Streak White 1.1.5 Porosity Highly Porous 1.1.6 Luster Dull 1.1.7 Compressive Strength Properties of F.. ⊕ Not Available Properties of Obsidian ⊕ 175 (Properties of..) ADD ⊕ 1.1.8 Cleavage Non-ExistentChalk is a sedimentary carbonate rock, a form of limestone composed of the mineral calcite. Marble is a metamorphic rock composed of recrystallized carbonate minerals, most commonly calcite or dolomite. Limestone is a sedimentary carbonate rock often composed of the skeletal fragments of marine organisms such as coral, foraminifera, and mollusks.It consists mainly of silicates (silicon and oxygen), phyllosilicates (potassium and aluminum silicate), and aluminosilicates (aluminum silicate). The term “slate” also refers to objects made from the rock, such as slate tablets or roofing tiles. The phrases “clean slate” and “blank slate” refer to slate’s use in chalkboards.Austin Chalk. In Eastern part of Trans-Pecos Texas and High Plains- Chalk and marl; chalk mostly microgranular calcite with minor foraminifera tests and Inoceramun prisms, averages ab out 85 percent calcium carbonate, ledge forming, grayish white, white; alternates with marl, bentonitic seams locally recessive; medium gray; pyrite nodules ...Gneiss is a foliated metamorphic rock identified by its bands and lenses of varying mineral composition. Some of these bands (or lenses) contain granular minerals that are bound together in an interlocking texture. Other bands contain platy or elongated minerals that show a preferred orientation that parallels the overall banding in the rock.Coal is a non-clastic sedimentary rock.They are the fossilized remains of plants and are in flammable black and brownish-black tones. Its main element is carbon, but it can also contain different elements such as hydrogen, sulfur and oxygen. Unlike coal minerals, it does not have a fixed chemical composition and crystal …The Chalk Group (often just called the Chalk) is the lithostratigraphic unit (a certain number of rock strata) which contains the Upper Cretaceous limestone succession in southern and eastern England. The same or similar rock sequences occur across the wider northwest European chalk 'province'. It is characterised by thick deposits of chalk, a soft porous …Apr 23, 2023 · Marl or the other name Marlstone is a calcium carbonate non-clastic sedimentary rock. It has containt variable of clays and silt. The dominant carbonate mineral in the most of the marls calcite, aragonite, dolomite and siderite. Iı belongs to the family of pelitic rocks (clays <0.02 mm, the fine particles in water sales) and a carbonate is a ... Chalk is a soft, white, porous, sedimentary carbonate rock, a form of limestone composed of the mineral calcite. Calcite is an ionic salt called calcium carbonate or CaCO3. It forms under reasonably deep marine conditions from the gradual accumulation of minute calcite shells (coccoliths) shed from micro-organisms called coccolithophores. Flint (a type of chert) is very common as bands ... Calcite is a carbonate mineral and the most stable polymorph of calcium carbonate (CaCO 3). It is a very common mineral, particularly as a component of limestone. Calcite defines hardness 3 on the Mohs scale of mineral hardness, based on scratch hardness comparison. Large calcite crystals are used in optical equipment, and limestone composed ...Chalk – A soft, white, porous sedimentary rock made of calcium carbonate ... The mineral composition of limestone is mainly calcite (accounting for more ...The Gneiss minerals are order into layer that seeing as band. Those layers are compositional banding, happens due to the fact the layers, or bands, are of different composition. The darker bands have incredibly extra mafic minerals (the ones containing more magnesium and iron). The lighter bands incorporate fantastically extra felsic minerals ...Sandstone. Sandstone is a sedimentary rock composed mainly of sand-sized mineral particles or rock fragments. It is a common rock type that is found all around the world, often forming in areas where there is a lot of sand accumulation, such as in deserts, riverbeds, or coastal areas. The mineral composition of sandstone can vary …Apr 20, 2023 · The mineralogical identification provided indicates mineral surface variation not recognized in such a quantitative amount, which is in turn of importance for modeling purposes for rock–fluid interaction in chalk (e.g., ). Surface mineral composition, charge, and ion-exchange capacity as well as brine pH and ionic composition are some of the ... Apr 23, 2023 · Marl or the other name Marlstone is a calcium carbonate non-clastic sedimentary rock. It has containt variable of clays and silt. The dominant carbonate mineral in the most of the marls calcite, aragonite, dolomite and siderite. Iı belongs to the family of pelitic rocks (clays <0.02 mm, the fine particles in water sales) and a carbonate is a ... A mineral is a naturally occurring, inorganic solid substance that has a specific chemical composition and a crystalline structure. Minerals are the building blocks of rocks, which are made up of one or more minerals. They are typically formed through various geological processes, such as crystallization from a melt (igneous), precipitation ...A piece of slate about 6 cm × 4 cm (2 + 1 ⁄ 2 in × 1 + 1 ⁄ 2 in). Slate is a fine-grained, foliated, homogeneous, metamorphic rock derived from an original shale-type sedimentary rock composed of clay or volcanic ash through low-grade, regional metamorphism.It is the finest-grained foliated metamorphic rock. Foliation may not correspond to the original …Sedimentary rocks composed of mostly but not all stable minerals would be considered: submature. Which grain size is found in argillite terrigenous rocks? silt/clay. Which grain size is found in rudite terrigenous rocks? gravel. Rock fragments are considered unstable. True. Which mineral is the most stable?But the biggest problem with the mines is the dust. “Once the harmful dust drops on the ground, it gathers and forms a hard shell,” says Zhang of the crust of hydromagnesite—caked-up chalk dust that has been exposed to water. And that dust has a huge impact on the environment and local people. De-Hui Zeng, an ecologist at the …Apr 25, 2019 · Quartz. Quartz is one of the most common minerals in the Earth's crust. It is made of silicon dioxide (SiO2), otherwise known as silica. Varieties of quartz based on color include: amethyst (purple), smoky quartz (grey), rose quartz (pink), and citrine (yellow-green). Quartz has a glassy luster and a hardness of 7. LIMESTONE CHALK | Limestone is made up of organic material, primarily calcium carbonate ... LOCALLY PROCESSED | Our rock and mineral samples are sourced from a ...It has the same chemical formula as other types of calcium carbonate, such as limestone, marble and chalk: CaCO3. The calcium, carbon and oxygen atoms can ...24 Sep 2020 ... A complementary objective is to describe the mineralogy and geochemistry of North Sea reservoir and non-reservoir chalk, as well as to model and.LIMESTONE CHALK | Limestone is made up of organic material, primarily calcium carbonate ... LOCALLY PROCESSED | Our rock and mineral samples are sourced from a ...Flint, occasionally flintstone, is a sedimentary cryptocrystalline form of the mineral quartz, [1] [2] categorized as the variety of chert that occurs in chalk or marly limestone. Flint was widely used historically to make stone tools and start fires . Flint occurs chiefly as nodules and masses in sedimentary rocks, such as chalks and limestones.Jan 24, 2023 · It is a soft limestone with high porosity and fine texture. Chalk is used to write on blackboards and can be crushed with bare hands. Chalk Limestone: The White Cliffs of Dover are composed of chalk. Coquina: It is a poorly cemented limestone consisting of sand-size fragments of calcium carbonate shells or coral debris. The grains in the rock ... Calcium phosphate (also known as hydroxyapatite) is the mineral component of bones and teeth and is a particularly good example of how organisms fabricate 'living' composite materials. Indeed, the different properties (such as stiffness) of bone are produced by varying the amount of organic component, mostly a fibrous protein called collagen, with …The maximum adsorption amount, Q max, is mainly determined by intrinsic particle factors, particularly particle specific surface area (SSA), and mineral composition.The finer the particle size is, the larger the SSA and the greater the adsorption capacity (Wang et al. 2006).Moreover, the surface structures of various minerals are …chalk chalk, mineral of calcium carbonate, similar in composition to limestone, but softer. It is characteristically a marine formation and sometimes occurs in great thickness; the chief constituents of these chalk deposits are the shells of minute animals called foraminiferans. Chalk has been laid down in all periods of geologic time, but most of the ...Nov 6, 2019 · Chert is a quite general term for noncrystalline siliceous rocks, and some subtypes have their own names and stories. In mixed calcareous and siliceous sediments, the carbonate and the silica tend to segregate. Chalk beds, the calcareous equivalent of diatomites, may grow lumpy nodules of chert of the type called flint. 9 Mei 2023 ... Limestone, marble, and chalk are composed of the compound Calcium Carbonate (CaCO3). Limestone and chalk: Limestone and chalk are ...Fossils. The putative galloanseran bird Austinornis lentus has been found in the Austin Chalk. The general absence of dinosaurs is a reflection of the Austin limestone being marine in origin, primarily composed of microscopic shell fragments from floating sea organisms known as "coccolithophores" (the same organisms that contributed to the White Cliffs of Dover, on the south coast of England).Gneiss is a foliated metamorphic rock identified by its bands and lenses of varying mineral composition. Some of these bands (or lenses) contain granular minerals that are bound together in an interlocking texture. Other bands contain platy or elongated minerals that show a preferred orientation that parallels the overall banding in the rock.Chalk is a soft, white, porous, sedimentary carbonate rock, a form of limestone composed of the mineral calcite. Calcite is an ionic salt called calcium carbonate or CaCO3. It forms under reasonably deep marine conditions from the gradual accumulation of minute calcite shells (coccoliths) shed from micro-organisms called coccolithophores. Flint (a type of chert) is very common as bands ...The geology channel explores the formation of rocks and gems, such as diamonds. Learn about geology with articles and video at HowStuffWorks. Advertisement Geology is the study of the composition and physical properties of rocks, minerals, ...Agricultural lime, also called aglime, agricultural limestone, garden lime or liming, is a soil additive made from pulverized limestone or chalk. The primary active component is calcium carbonate. Additional chemicals vary depending on the mineral source and may include calcium oxide. Unlike the types of lime called quicklime (calcium oxide ...Streak is the color of rock when it is crushed or powdered. The streak of Chalk is white whereas its fracture is not available. Luster of Chalk is the interaction of light with the surface of Chalk. Luster of Chalk is dull. Chalk cleavage is non-existent. The specific gravity of Chalk is 2.3-2.4. Chalk is opaque in nature whereas its toughness ...Chalk Chemical Composition. Chemical composition of chalk is calcium carbonate and with minor learn sludge and clays minerals. It is formed to to sea by sub-microscopic plankton, which fall until one sea floor and are then consolidated and compressed during diagenesis into rock. Chalk FormationThe potential new mineral appears dark grey and is peppered with tiny metallic chunks. (Image credit: Bindi et al. 2023, (CC BY 4.0) ) During their analysis, the researchers also tried, and failed ...Shale is a laminated or fissile clastic sedimentary rock that composed of predominance of silt and clay other minerals , especially quartz and calcite. Characteristic properties of shale is breaks along thin laminae or parallel layering or bedding called fissility. It is most abundant sedimentary rock. The composition (silt and clay) of shale ...Comments: In Eastern part of Trans-Pecos Texas and High Plains- Chalk and marl; chalk mostly microgranular calcite with minor foraminifera tests and Inoceramun prisms, averages ab out 85 percent calcium carbonate, ledge forming, grayish white, white; alternates with marl, bentonitic seams locally recessive; medium gray; pyrite nodules common, weather to limonite; thickness 325-420 ft.During this process, the rock remains mostly in the solid state, but gradually recrystallizes to a new texture or mineral composition. The protolith may be an igneous, sedimentary, or existing metamorphic rock. Metamorphic rocks make up a large part of the Earth's crust and form 12% of the Earth's land surface. Certain minerals react differently to each type of stress. Since tenacity is composed of several reactions to various stresses, it is possible for a mineral to have more than one type of tenacity. The different forms of tenacity are: Brittle - If a mineral is hammered and the result is a powder or small crumbs, it is considered brittle. Brittle ... chert and flint, very fine-grained quartz ( q.v. ), a silica mineral with minor impurities. Several varieties are included under the general term chert: jasper, chalcedony, agate ( qq.v. ), flint, porcelanite, and novaculite. Flint is gray to black and nearly opaque (translucent brown in thin splinters) because of included carbonaceous matter.Chalk Chemical Composition. Chemical composition of chalk is calcium carbonate and with minor learn sludge and clays minerals. It is formed to to sea by sub-microscopic plankton, which fall until one sea floor and are then consolidated and compressed during diagenesis into rock. Chalk FormationAug 11, 2023 · Augen gneiss is not a pure substance but a mixture of rocks. Its chemical composition will change depending on where it comes from. It is an igneous rock that is a mixture of others. Have you noticed an increase in the number of adorable chalk drawings adorning the sidewalks on your quarantine strolls around the neighborhood lately? Cooped-up kids (and more than a few adults) are taking to the sidewalks to throw down a ...Figure 5.3.1 5.3. 1: Enlarged image of frosted and rounded windblown sand grains. Medium-grained rocks composed mainly of sand are called sandstone, or sometimes arenite if well sorted. Sediment grains in sandstone can having a wide variety of mineral compositions, roundness, and sorting.Coquina is a sedimentary rock composed almost entirely of sand-size fossil debris. The fossils are usually mollusk or gastropod shells and shell fragments. Brachiopod, trilobite, coral, ostracod and other invertebrate shell debris is present in many coquinas. The fossil debris of coquina is composed of calcium carbonate, making coquina a ...Limestone is composed mostly of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate (CaCO 3). Dolomite, CaMg(CO 3) 2, is an uncommon mineral in limestone, and siderite or other carbonate minerals are rare. However, the calcite in limestone often contains a few percent of magnesium. Calcite in limestone is ...from the Upper Eagle Ford Shale and the latter values coming from the Austin Chalk. Sulfur percent composition ranged from 0%-20% and had similar trends as Magnesium which had values from 0.04% to 4.8%. The Austin Chalk contained great values of pyrite, illite, quartz, calcite, and dolomite. Trace element concentrations suggest that the Red shale. Shale is a laminated or fissile clastic sedimentary rock that composed of predominance of silt and clay other minerals, especially quartz and calcite.Characteristic properties of shale is breaks along thin laminae or parallel layering or bedding called fissility. It is most abundant sedimentary rock.The composition (silt and …the mineral phase and eggshell matrix proteins has been . ... brown-shelled eggs: mineral composition of uterine fluid . and rate of protoporphyrin deposition. Poult Sci 70, 1236-45 (1991)Sep 30, 2016 · The rock is granite. Study its appearance, and note that it also comes under Division C. Identify the black, or dark, or green mineral as hornblende or pyroxene, by good cleavage and hardness. Note light-colored crystals, hard and with good cleavage, as feldspar. The specimen is diorite, gabbro, or diabase, hard to distinguish from one another. Dec 1, 2021 · Burrowed marly chalk (lithofacies 1) has the best reservoir quality, with a mean porosity of 6.2% and a geometric mean permeability of 351 nd. Burrowed chalky marl to marly chalk (lithofacies 2) has the second-best reservoir quality, with mean porosity being 5.5% and geometric mean permeability being 214 nd. Chalk is an non-clastic oxidize sedimentary rock that is form concerning limestones compesed of the mineral calcite. It is soft, fine-grained and easily pulverized. Color is …Compositional: Calcite Color: Pallid Miscellaneous: Massive, Earthy; Reacts in HCl; Hardness < Glass Depositional Environment: Deep Ship Color: white-to-grayish Chalk Classification Natural chalk Natural chalk occurring for deep sea conditions and consists of gradual array of very small calcite crockery.Definitions. Chalk . To rub or cover with chalk, as the tip of a billiard cue. 1. Gypsum . Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO4·2H2O. It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, blackboard/sidewalk chalk, and drywall.Siltstone, also known as aleurolite, is a clastic sedimentary rock that is composed mostly of silt.It is a form of mudrock with a low clay mineral content, which can be distinguished from shale by its lack of fissility.. Although its permeability and porosity is relatively low, siltstone is sometimes a tight gas reservoir rock, an unconventional reservoir for natural gas that …Composition. Quartz, Feldspar. Color. Tan to brown. Miscellaneous. Rounded clasts in a fine- to medium-grained matrix; Immature. Depositional Environment. Alluvial Fan, Glacial (unstratified till), or Braided Stream. Type Sedimentary Rock Origin Detrital/Clastic Texture Clastic; Coarse-grained (2 – 64 mm) Composition Quartz, Feldspar Color ...Granite is a type of igneous rock that is composed of several minerals. The mineral composition of granite can vary depending on the location where it was formed, but the most common minerals found in granite include: Feldspar: This is the most common mineral found in granite, accounting for up to 60% of the rock’s composition.The geology channel explores the formation of rocks and gems, such as diamonds. Learn about geology with articles and video at HowStuffWorks. Advertisement Geology is the study of the composition and physical properties of rocks, minerals, ...Elastic moduli versus porosity for water saturated and dry chalk. All samples are chalk with more than 90% carbonate. (A), (B) P-wave modulus, M, as calculated from P-wave velocity and density.An X-ray fluorescence (XRF) spectrometer is an x-ray instrument used for routine, relatively non-destructive chemical analyses of rocks, minerals, sediments and fluids. It works on wavelength-dispersive spectroscopic principles that are similar to an electron microprobe ( EPMA ). However, an XRF cannot generally make analyses at the …Turquoise is an opaque, blue-to-green mineral that is a hydrous phosphate of copper and aluminium, with the chemical formula Cu Al 6 (PO 4) 4 8 ·4H 2 O.It is rare and valuable in finer grades and has been prized as a gemstone for millennia due to its unique hue.. Like most other opaque gems, turquoise has been devalued by the introduction of …Composition A typical chalk is a fine-grained carbonate rock (a lime mudstone or micrite ), the lithified equivalent of pelagic carbonate oozes recorded from ODP boreholes in present-day oceans. The sediment is dominated by debris derived from coccolithophorid algae that comprise a spherical calcareous test (coccosphere) up to several tens of ...Turquoise is an opaque, blue-to-green mineral that is a hydrous phosphate of copper and aluminium, with the chemical formula Cu Al 6 (PO 4) 4 8 ·4H 2 O.It is rare and valuable in finer grades and has been prized as a gemstone for millennia due to its unique hue.. Like most other opaque gems, turquoise has been devalued by the introduction of …Complete answer: Chalk is a common name of the compound calcium carbonate. Its chemical formula is CaCO3 C a C O 3. Calcium carbonate is a form of limestone. Chalk is a common substance found everywhere. It is a soft, highly porous, white sedimentary carbonate rock of limestone. It is composed of calcite shells or skeletons of planktons.Apr 25, 2019 · Quartz. Quartz is one of the most common minerals in the Earth's crust. It is made of silicon dioxide (SiO2), otherwise known as silica. Varieties of quartz based on color include: amethyst (purple), smoky quartz (grey), rose quartz (pink), and citrine (yellow-green). Quartz has a glassy luster and a hardness of 7. Licking a sample will quickly distinguish the two, as halite has the same composition as table salt and a very distinctive ‘salty’ taste. For those who dislike the idea of licking mineral samples, the two minerals can also be distinguished by their cleavage patterns. Halite has three perfect cleavages that form at right angles to form cubes.7.1 Weathering. Sediments and sedimentary minerals are products of weathering that involves the physical degradation and chemical alteration of rocks at the Earth’s surface. It is caused by chemical reactions involving air, water, salt, or acid, by freezing and thawing, and by plants and animals.Limestone. Limestone is a very common sedimentary rock consisting of calcium carbonate (more than 50%). It is the most common non-siliciclastic ( sandstone and shale are common siliciclastic rocks) sedimentary rock. Limestones are rocks that are composed of mostly calcium carbonate (minerals calcite or aragonite).Basalt is known for its dark color, typically ranging from black to dark gray, and its fine-grained texture. It is composed mostly of minerals such as pyroxene, plagioclase feldspar, and sometimes olivine. Basalt can have a range of compositions, but it is typically rich in iron and magnesium, and low in silica.Diamond is a naturally occurring mineral composed of carbon atoms arranged in a crystalline lattice structure. As a result, it possesses a number of unique chemical properties, including: Hardness : Diamond is the hardest known natural substance, with a rating of 10 on the Mohs hardness scale.Groundwater Chemistry. The natural groundwater chemistry results from the chemical composition of recharge water (i.e. precipitation or infiltrated surface water) that is modified in the soil, the unsaturated zone and the aquifer (or aquitard) by biogeochemical reactions involving interrelated factors such as soil composition, aquifer mineralogy, groundwater …Sandstone. Sandstone is a sedimentary rock composed mainly of sand-sized mineral particles or rock fragments. It is a common rock type that is found all around the world, often forming in areas where there is a lot of sand accumulation, such as in deserts, riverbeds, or coastal areas. The mineral composition of sandstone can vary …organogenic calcite (chalk) in the cement stone composition results in a change of the phase composition of the hydrates of new formations, i.e. it results ...Chalk is composed of the shells of such minute marine organisms as foraminifera, coccoliths, and rhabdoliths. The purest varieties contain up to 99 percent calcium carbonate in the form of the mineral calcite.
Chalk is a soft, white, porous, sedimentary carbonate rock. It is a form of limestone composed of the mineral calcite and originally formed deep under the sea by the compression of microscopic plankton that had settled to the sea floor.. Definition informative speech
Granite is a type of igneous rock that is composed of several minerals. The mineral composition of granite can vary depending on the location where it was formed, but the most common minerals found in granite include: Feldspar: This is the most common mineral found in granite, accounting for up to 60% of the rock’s composition.Aug 27, 2023 · Granite is a type of igneous rock that is composed of several minerals. The mineral composition of granite can vary depending on the location where it was formed, but the most common minerals found in granite include: Feldspar: This is the most common mineral found in granite, accounting for up to 60% of the rock’s composition. 24 Sep 2020 ... A complementary objective is to describe the mineralogy and geochemistry of North Sea reservoir and non-reservoir chalk, as well as to model and.Limestone is composed mostly of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate (CaCO 3). Dolomite, CaMg(CO 3) 2, is an uncommon mineral in limestone, and siderite or other carbonate minerals are rare. However, the calcite in limestone often contains a few percent of magnesium. Calcite in limestone is ...Chalk is a non-clastic carbonate sedimentary rock that is form of limestones compesed starting the ore calcite. Methamphetamine is fine-grained and ease pulverized.Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO 4 ·2H 2 O. It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, drywall and blackboard or sidewalk chalk. Gypsum also crystallizes as translucent crystals of selenite.Mineral composition, and aid in classical log analysts used in Jurassic sandstone of the northern. North Sea. SPWLA 19. Annual Meeting, pp. 1-35. Okaa P.M. ...The composition of the clasts. If all the clasts are the same type of rock or mineral), the rock is categorized as monomictic conglomerate. If the clasts are made up of two or more rocks or minerals, the rock is a polymictic conglomerate. The size of the clasts. Rock comprised of large clasts is cobble conglomerate.W H ATOD IN SLB In Part 1, you will review some common sedimentary rock-forming minerals. In Part 2, you will study the textures and mineralogy of a variety of sedimentary rocks and learn how to identify them. In Part 3, you will identify a group of unknown sedimentary minerals and rocks. WH A TY OU R EXPC D KN W I expect you to be able …Quartzite, a type of metamorphic rock Metamorphic rock, deformed during the Variscan orogeny, at Vall de Cardós, Lérida, Spain. Metamorphic rocks arise from the transformation of existing rock to new types of rock in a process called metamorphism.The original rock is subjected to temperatures greater than 150 to 200 °C (300 to 400 °F) and, often, …Magnetic minerals – minerals which show magnetic properties. Two examples are magnetite and hematite Metamorphic rocks - formed from igneous, sedimentary, or other metamorphic rocks which contain minerals that have been changed by heat, pressure, or chemical action Mineral - occur in nature and have definite chemical compositions.