Term
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Definition
Mineral Amethyst
- LUSTER VITREOUS/GLOSSY
- MOHS SCALE HARDNESS 7–LOWER IN IMPURE VARIETIES
- CLEAVAGE NONE
- FRACTURE CONCHOIDAL
- COLOR PURPLE, VIOLET
- STREAK WHITE
- SOLUBILITY INSOLUBLE IN COMMON SOLVENTS, CRYSTAL HABIT 6-SIDED PRISM ENDING IN 6-SIDED PYRAMID (TYPICAL)
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Definition
Mineral #3: AUGITE (PYROXENE)
- GREENISH BLACK TO BLACK
- HARDNESS = 5-6 (harder than nail)
- CLEAVAGE (2 DIRECTIONS)
- SPECIFIC GRAVITY = 3.4
- NON METALLIC |
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Term
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Definition
Mineral #2: BIOTITE
- HARDNESS = 2.5-3 (HARDER THAN FINGERNAIL, SOFTER THAN GLASS)
- CLEAVAGE ( ONE DIRECTION)
- DARK BROWN TO BLACK
- ELASTIC IN THIN SHEETS: BLACK MICA
- NON METALLIC |
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Term
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Definition
Mineral #4: CALCITE
- WHITE, YELLOWISH TO COLORLESS
- HARDNESS =3 (HARDER THAN FINGERNAIL, SOFTER THAN GLASS)
- CLEAVAGE (3 DIRECTIONS, 75 DEGREES)
- NON METALLIC |
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Term
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Definition
Mineral #13: FLUORITE
- NON METALLIC
- YELLOW, PURPLE, GREEN, COLORLESS
- HARDNESS =4
- WHITE STREAK
- TRANSLUCENT TO TRANSPARENT
- CLEAVAGE (4 DIRECTIONS) |
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Term
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Definition
Mineral # 7: GALENA
- GRAY-BLACK STREAK
- SILVERY GRAY COLOR
- HARDNESS 2.5
- CLEAVAGE (CUBIC)
- METALLIC |
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Term
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Definition
Mineral # 9: GARNET
- CLEAVAGE POOR OR ABSENT ( CONCHOIDAL FRACTURE)
- RED TO REDISH BROWN
- HARDNESS= 6.5-7
- GLASSY LUSTER
- NON METALLIC |
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Term
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Definition
Mineral # 8: GYPSUM
- CLEAVAGE (3 DIRECTIONS)
- WHITE TO TRANSPARENT
- HARDNESS =2
- FLEXIBLE IN SHEETS BUT NOT ELASTIC |
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Term
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Definition
Mineral #17: HALITE
- CLEAVAGE (3 DIRECTIONS)
- WHITE TO COLORLESS
- HARDNESS = 2.5
- SALTY TASTE |
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Term
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Definition
Mineral #16: HEMATITE
-NON METALLIC
- CLEAVAGE POOR OR ABSENT
- HARDNESS = 1-5
- REDDISH BROWN
- RED STREAK
- EARTHY APPEARANCE |
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Term
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Definition
Mineral Hornblende/ Amphibole
-LUSTER VITREOUS TO DULL
- MOHS SCALE HARDNESS 5–6
- CLEAVAGE IMPERFECT AT 56 AND 124 DEGREES
- FRACTURE UNEVEN
- COLOR BLACK/DARK GREEN
- STREAK PALE GRAY, GRAY-WHITE
- CRYSTAL HABIT HEXAGONAL/GRANULAR, SOME METALS VARY IN THEIR OCCURRENCE AND MAGNITUDE |
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Term
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Definition
Mineral # 12: MAGNETITE
- GRAY-BLACK STREAK
- BLACK IN COLOR
- MAGNETIC
- HARDNESS = 6
- OFTEN GRANULAR
- METALLIC |
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Term
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Definition
Mineral # 14: MUSCOVITE
- CLEAVAGE (1 DIRECTION)
- HARDNESS = 2 -2.5
- TRANSPARENT AND ELASTIC IN THIN SHEETS
- LIGHT COLORED MICA
- NON METALLIC |
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Term
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Definition
Mineral #5: OLIVINE
- CLEAVAGE POOR OR ABSENT
- OLIVE GREEN
- HARDNESS= 6.5 -7
- SMALL GLASSY GRAINS
- NON METALLIC |
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Term
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Definition
Mineral 15#: PLAGIOCLASE FELDSPAR
- NON METALLIC
-CLEAVAGE ( 2 DIRECTIONS)
- HARDNESS = 6
-WHITE TO DARK GRAY
- STRIATIONS ON SOME |
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Term
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Definition
Mineral #1: POTASSIUM FELDSPAR (ORTHOCLASE)
- HARDNESS =6 (Harder than glass >5.5)
- CLEAVAGE PRESENT (2 directions right angles)
- PINK OR WHITE
- LACKS STRIATIONS
- NON METALIC LUSTER |
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Term
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Definition
Mineral # 11: PYRITE
- HARDNESS = 6
- GREENISH-BLACK STREAK
- BRASS/YELLOW IN COLOR
- AGGREGATE OF CUBIC CRYSTALS
- METALLIC LUSTER |
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Term
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Definition
Mineral #6: QUARTZ
- HARDNESS = 7 (HARDER THAN GLASS)
- ANY COLOR (WHITE, PINK, GRAY, VOILET)
- GLASSY APPEARANCE
- NON METALLIC |
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Term
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Definition
Mineral Specular Hematite
- SPECULAR HEMATITE IS A VARIETY OF HEMATITE WITH A BLUE-GRAY COLOR AND BRIGHT METALLIC LUSTER.
- WHILE THE FORMS OF HEMATITE VARY, THEY ALL HAVE A RUST-RED STREAK. HEMATITE IS HARDER THAN PURE IRON, BUT MUCH MORE BRITTLE. MAGHEMITE IS A HEMATITE- AND MAGNETITE-RELATED OXIDE MINERAL |
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Term
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Definition
Mineral #10: TALC
- CLEAVAGE POOR OR ABSENT
- WHITE, PINK, GREEN
- HARDNESS = 1-2
- SOAPY FEEL
- PEARLY LUSTER
- NON METALLIC |
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Term
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Definition
Igneous 1 GABBRO
- MORE MAFIC MINERALS
- PHANERITIC- coarse grained
- MCI = 45-85
- INTRUSIVE |
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Term
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Definition
Igneous 2 PUMICE
- INTERMEDIATE OR FELSIC
- ABUNDANT TINY VESICLES- LIKE MERINGUE
- FLOATS IN WATER
- EXTRUSIVE
- VESICULAR |
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Term
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Definition
Igneous 3 ANDESITE
- INTERMEDIATE (MCI = 15=45)
- GREEN TO GRAY
- APHANITIC – fine grained
- EXTRUSIVE |
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Term
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Definition
Igneous 4 GRANITE
- MORE FELDSPAR THAN MAFIC MINERALS
- PHANERITIC- course grained
- K-SPAR > PLAGIOCLASE
- QUARTZ PRESENT |
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Term
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Definition
Igneous 5 DIORITE
- INTRUSIVE
- PHANERITIC: COURSE- GRAINED
- MORE FELSIC MINERALS
- PLAGOICLASE > K-SPAR |
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Term
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Definition
Igneous 6 BASALT
- EXTRUSIVE
-APHANITIC: fine grained
- MAFIC (MCI> 45,
- dark grey to black |
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Term
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Definition
Igneous 7 VESICULAR BASALT
- EXTRUSIVE
- VESICULAR (air bubbles)
- MAFIC (MCI > 45)
- DARK GREY TO BLACK
- HAS A FEW SCATTERED VESICLES |
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Term
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Definition
Igneous 8 OBSIDIAN
- GLASSY TEXTURE
- EXTRUSIVE
- COOLED VERY RAPIDLY |
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Term
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Definition
Igneous 9 RHYOLITE
- APHANITIC: fine grained
- EXTRUSIVE
- FELSIC, (MCI = 0-15)
- PINK, WHITE, OR PALE BROWN |
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Term
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Definition
Igneous 10 PORPHYRITIC RHYOLITE
- PHENOCRYSTS ( crystals larger than the finer grained main part of the rock)
- APHANITIC TEXTURE, WITH PHENOCRYSTS
- EXTRUSIVE (MAY BE INTRUSIVE)
- FELSIC (MCI= 0-15)
- PINK, WHITE, PALE BROWN |
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Term
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Definition
Igneous Scoria
- SCORIA IS A HIGHLY VESICULAR, DARK COLORED VOLCANIC ROCK THAT MAY OR MAY NOT CONTAIN CRYSTALS (PHENOCRYSTS). IT IS TYPICALLY DARK IN COLOR (GENERALLY DARK BROWN, BLACK OR PURPLISH RED), AND BASALTIC OR ANDESITIC IN COMPOSITION. SCORIA IS RELATIVELY LOW IN MASS AS A RESULT OF ITS NUMEROUS MACROSCOPIC ELLIPSOIDAL VESICLES, BUT IN CONTRAST TO PUMICE, ALL SCORIA HAS A SPECIFIC GRAVITY GREATER THAN 1, AND SINKS IN WATER. |
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Term
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Definition
Igneous Tuff
- TUFF IS TECHNICALLY A SEDIMENTARY ROCK FORMED BY THE ACCUMULATION OF VOLCANIC ASH PLUS PUMICE OR SCORIA.
- TUFF IS SO CLOSELY ASSOCIATED WITH VOLCANISM THAT IT IS USUALLY DISCUSSED ALONG WITH THE TRULY IGNEOUS ROCKS AROUND IT. TUFF TENDS TO FORM WHEN ERUPTING LAVAS ARE STIFF AND HIGH IN SILICA, WHICH HOLDS THE VOLCANIC GASES IN BUBBLES RATHER THAN LETTING IT ESCAPE. THE BRITTLE LAVA IS READILY SHATTERED INTO JAGGED PIECES, COLLECTIVELY CALLED TEPHRA (TEFF-RA) OR VOLCANIC ASH. FALLEN TEPHRA MAY BE REWORKED BY RAINFALL AND STREAMS. TUFF IS A ROCK OF GREAT VARIETY AND TELLS THE GEOLOGIST A LOT ABOUT CONDITIONS DURING THE ERUPTIONS THAT GAVE BIRTH TO IT. |
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Term
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Definition
Sedimentary 1 ARKOSE
- SANDSTONE, WITH MOSTLY FELDSPAR SAND
- GRAIN SIZE: 1/16 – 2 mm
- MAY CONTAIN FOSSILS
- DETRITAL sediment grains, fragmented rocks and or silicate mineral crystals
- CLASTIC |
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Term
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Definition
Sedimentary 2 CALCARENITE (also called fossilferous limestone)
- BIOCHEMICAL (BIOCLASTIC) sediment grains, fragments/shells of organisms
- SHELLS AND SHELL./CORAL FRAGMENTS
- MOSTLY SAND SIZED SHELL FRAGMENTS
- OFTEN CONTAINS A FEW LARGER FOSSIL SHELLS
- CLASTIC |
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Term
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Definition
Sedimentary 3 COAL
- BIOCHEMICAL (BIOCLASTIC) sediment grains: fragments/shells of organisms
- PLANT FRAGMENTS AND CHARCOAL
- BLACK, LAYERED, BRITTLE ROCK
- FOSSIL PLANT FRAGMENTS MAY BE VISIBLE
- CLASTIC |
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Term
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Definition
Sedimentary 4 SHALE
- DETRITAL sediment grains, fragmented rocks and or silicate mineral crystals
- GRAIN SIZE = MUD < 1/16 mm
- MOSTLY CLAY, MAY CONTAIN FOSSILS
- FISSILE (splits easily into layers)
- MUDSTONE
- CLASTIC |
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Term
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Definition
Sedimentary 5 CONGLOMERATE
- DETRITAL sediment grains, fragmented rocks and or silicate mineral crystals
- MOSTLY SUBROUND AND/OR WELL ROUNDED GRAINS
- GRAIN SIZE = LARGER THAN 2 mm
- SANDSTONE
- CLASTIC |
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Term
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Definition
Sedimentary 6 CHERT
- MINERAL CRYSTALS (inorganic) and/or CHEMICAL RESIDUES (ex rust)
- MICROCRYSTALLINE VARIETIES OF QUARTZ (flint, chalcedony, chert, jasper)
- FRACTURE, HARDER THAN GLASS, GREY, BLACK, BROWN,
- CHEMICAL SEDIMENTARY ROCKS, NON- CLASTIC |
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Term
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Definition
Sedimentary 7 COQUINA
- BIOCHEMICAL, (BIOCLASTIC) sediment grains: fragments/shells of organisms
- SHELLS AND SHELL/CORAL FRAGMENTS (&/OR calcareous microfossils)
- MOSTLY GRAVEL SIZED SHELLS AND SHELL OR CORAL FRAGMENTS
- CLASTIC
- A TYPE OF LIMESTONE |
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Term
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Definition
Sed 8 BRECCIA
- DETRITAL sediment grains, fragmented rocks and or silicate mineral crystals
- MOSTLY ANGULAR AND/OR SUBANGULAR GRAINS
- GRAIN SIZE = LARGER THAN 2 mm
- SANDSTONE
- CLASTIC |
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Term
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Definition
Sed 9 SANDSTONE
- SAND GRAINS 1/16- 2 mm
- MAY CONTAIN FOSSILS
- DETRITAL
- CLASTIC
- WELL SORTED, ROUNDED GRAINS |
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Term
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Definition
Sed 10 MICRITE
- BIOCHEMICAL, (BIOCLASTIC) sediment grains: fragments/shells of organisms
- SHELLS AND SHELL/CORAL FRAGMENTS (&/OR calcareous microfossils)
- NO VISIBLE GRAINS IN MOST OF THE ROCK
- FRACTURES,
- MAY CONTAIN A FEW VISIBLE IN THE MICRITE
- LIMESTONE
- CLASTIC |
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Term
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Definition
Sedimentary Limestone
- Limestone is a sedimentary rock composed largely of the minerals calcite and aragonite, which are different crystal forms of calcium carbonate (CaCO3). Many limestones are composed from skeletal fragments of marine organisms such as coral or foraminifera. - Limestone makes up about 10% of the total volume of all sedimentary rocks. The solubility of limestone in water and weak acid solutions leads to karst landscapes, in which water erodes the limestone over thousands to millions of years. Most cave systems are through limestone bedrock.
- Limestone has numerous uses: as a building material, as aggregate for the base of roads, as white pigment or filler in products such as toothpaste or paints and as a chemical feedstock.
- Like most other sedimentary rocks, most limestone is composed of grains. Most grains in limestone are skeletal fragments of marine organisms such as coral or foraminifera. Other carbonate grains comprising limestones are ooids, peloids, intraclasts, and extraclasts. These organisms secrete shells made of aragonite or calcite, and leave these shells behind after the organisms die.
-Limestone often contains variable amounts of silica in the form of chert (chalcedony, flint, jasper, etc.) or siliceous skeletal fragment (sponge spicules, diatoms, radiolarians), and varying amounts of clay, silt and sand (terrestrial detritus) carried in by rivers.
- Some limestones do not consist of grains at all, and are formed completely by the chemical precipitation of calcite or aragonite, i.e. travertine. Secondary calcite may be deposited by supersaturated meteoric waters (groundwater that precipitates the material in caves). This produces speleothems, such as stalagmites and stalactites. Another form taken by calcite is oolitic limestone, which can be recognized by its granular (oolite) appearance.
- The primary source of the calcite in limestone is most commonly marine organisms. Some of these organisms can construct mounds of rock known as reefs, building upon past generations. Below about 3,000 meters, water pressure and temperature conditions cause the dissolution of calcite to increase nonlinearly, so limestone typically does not form in deeper waters (see lysocline). Limestones may also form in both lacustrine and evaporite depositional environments.[2][3] |
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Term
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Definition
Sedimentary Mudstone
- Mudstone (also called mudrock) is a fine grained sedimentary rock whose original constituents were clays or muds. Grain size is up to 0.0625 mm (0.0025 in) with individual grains too small to be distinguished without a microscope. With increased pressure over time the platey clay minerals may become aligned, with the appearance of fissility or parallel layering. This finely bedded material that splits readily into thin layers is called shale, as distinct from mudstone. The lack of fissility or layering in mudstone may be due either to original texture or to the disruption of layering by burrowing organisms in the sediment prior to lithification. Mud rocks, such as mudstone and shale comprise some 65% of all sedimentary rocks. Mudstone looks like hardened clay and, depending upon circumstances under which it was formed, it may show cracks or fissures, like a sun-baked clay deposit.[1]
They can be separated into these categories:
- Siltstone - greater than half of the composition is silt-sized particles.
-Claystone - greater than half of the composition is clay-sized particles.
-Mudstone - hardened mud; a mix of silt and clay sized particles. Mudstone can include: Shale - exhibits lamination or fissility.
-Argillite - has undergone low grade metamorphism. |
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Term
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Definition
Sedimentary Oolitic Limestone
- Composition
Calcite - CaCO3, formed into small pearl-like spheres, constructed as concentric layers. This is a chemical rocks, precipitated from warm, supersaturated marine water.
- Description
A pure oolitic limestone with spar cement. The oolites are white, rounded, and concentrically layered, in the sand sized range. In some of the broken oolites we can see the seed in the middle which began the oolite, and the concentric layers by which the oolite was built. In the unbroken examples the oolite just looks like a tiny pearl. The spar cement is clear calcite precipitated between the oolites by ground water after deposition. It looks transparent or slightly gray, almost like a clear glue binding the oolites together.
- Formation & Environments
Oolites form today in warm, supersaturated, shallow, highly aggitated marine water. They are commonly associated with zones of high tidal activity in a subtidal or lower intertidal environment.
The mechanism of formation is to begin with a seed of some sort, perhaps a shell fragment. The strong currents wash this seed around on the bottom where it accumulates a layer of chemically precipitated calcite from the supersaturated water. Only this process is going on with uncounted trillions of oolites. The oolites are commonly found in large dunes (megaripples); if you could be there you could scoop up the oolites in your arms and hands.
The concentric layers is formed as the oolites are alternately exposed to pick up a concentric layer, and then buried to set the layer. The next exposure then adds another layer. |
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Term
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Definition
METAMORPHIC 1: GNEISS
- FOLIATED
- MEDIUM TO COURSE GRAINED
- GNESSIC BANDING, MINERALS SEGREGATED INTO LAYERS, CRYSTALLINE TEXTURE
- VISIBLE CRYSTALS OF 2 OR MORE MINERALS IN ALTERNATING LIGHT & DARK FOLIATED LAYERS
- PARENT ROCK: MUDSTONE, SHALE, SLATE, PHYLLITE, SCHIST, GRANITE OR DIORITE |
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Term
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Definition
METAMORPHIC 2: SCHIST
- FOLIATED
- MEDIUM TO COURSE GRAINED
- SCHISTOSITY: foliation formed by alignment of visible crystals- rocks break along scaly foliation surfaces
- CRYSTALLINE TEXTURE
- PARENT ROCK: mudstone, shale, slate, or phyllite |
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Term
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Definition
METAMORPHIC 3: SLATE
- FOLIATED
- FINE-GRAINED OR NO VISIBLE GRAINS
- FLAT SLATY CLEAVAGE , WELL-DEVELOPED
- DULL LUSTER
- PARENT ROCK= MUDSTONE OR SHALE |
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Term
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Definition
METAMORPHIC 4: GARNET SCHIST
- FOLIATED
- MEDIUM TO COURSE GRAINED
- SCHISTOSITY: foliation formed by alignment of visible crystals- rocks break along scaly foliation surfaces
- CRYSTALLINE TEXTURE
- PARENT ROCK: mudstone, shale, slate, or phyllite
- CRYSTAL GRAINS OF GARNET |
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Term
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Definition
METAMORPHIC 5: QUARTZITE
- NON-FOLIATED
- FINE TO COURSE-GRAINED
- SANDY TEXTURE
- QUARTZ SAND GRAINS FUSED TOGETHER
- GRAINS DON’T RUB OFF LIKE SANDSTONE
- LIGHT COLORED
- PARENT ROCK= SANDSTONE |
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Term
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Definition
METAMORPHIC 6: PHYLLITE
- FOLIATED
- FINE GRAINED TO NO VISIBLE GRAINS
- PHYLLITE TEXTURE WELL DEVELOPED MORE THAN SLATY CLEAVAGE
- Breaks along wrinkled or wavy foliation surfaces with shiny metallic luster
- PARENT ROCK: MUDSTONE SHALE OR SLATE |
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Term
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Definition
METAMORPHIC 7: MARBLE
- NON- FOLIATED
- FINE TO COURSE GRAINED
- MICROCRYSTALLINE (resembling a sugar cube) OR MEDIUM TO COARSE CRYSTALLINE TEXTURE
- CALCITE (OR DOLOMITE) CRYSTALS (nearly equal size and tightly fused together)
- CALCITE EFFERVESCES ONLY IF POWDERED
- PARENT ROCK= LIMESTONE |
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Term
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Definition
Metamorphic Amphibolite
- AMPHIBOLITE ( /ÆMˈFɪBƏLAɪT/) IS THE NAME GIVEN TO A METAMORPHIC ROCK CONSISTING MAINLY OF AMPHIBOLE, ESPECIALLY THE SPECIES HORNBLENDE AND ACTINOLITE. A HOLOCRYSTALLINE PLUTONIC IGNEOUS ROCK COMPOSED PRIMARILY OF HORNBLENDE AMPHIBOLE IS CALLED A HORNBLENDITE, WHICH ARE USUALLY CRYSTAL CUMULATES. ROCKS WITH >90% AMPHIBOLES WHICH HAVE A FELDSPAR GROUNDMASS MAY BE A LAMPROPHYRE.
-AMPHIBOLITE IS A GROUPING OF ROCKS COMPOSED MAINLY OF AMPHIBOLE AND PLAGIOCLASE FELDSPARS, WITH LITTLE OR NO QUARTZ. IT IS TYPICALLY DARK-COLORED AND HEAVY, WITH A WEAKLY FOLIATED OR SCHISTOSE (FLAKY) STRUCTURE. THE SMALL FLAKES OF BLACK AND WHITE IN THE ROCK OFTEN GIVE IT A SALT-AND-PEPPER APPEARANCE.
-AMPHIBOLITES NEED NOT BE DERIVED FROM METAMORPHOSED MAFIC ROCKS. BECAUSE METAMORPHISM CREATES MINERALS BASED ENTIRELY UPON THE CHEMISTRY OF THE PROTOLITH, CERTAIN 'DIRTY MARLS' AND VOLCANIC SEDIMENTS MAY ACTUALLY METAMORPHOSE TO AN AMPHIBOLITE ASSEMBLAGE. DEPOSITS CONTAINING DOLOMITE AND SIDERITE ALSO READILY YIELD AMPHIBOLITES (TREMOLITE-SCHISTS, GRUNERITE-SCHISTS, AND OTHERS) ESPECIALLY WHERE THERE HAS BEEN A CERTAIN AMOUNT OF CONTACT METAMORPHISM BY ADJACENT GRANITIC MASSES. METAMORPHOSED BASALTS CREATE ORTHO-AMPHIBOLITES AND OTHER CHEMICALLY APPROPRIATE LITHOLOGIES CREATE PARA-AMPHIBOLITES.
-TREMOLITE, WHILE IT IS A METAMORPHIC AMPHIBOLE, IS DERIVED MOST USUALLY FROM HIGHLY METAMORPHOSED ULTRAMAFIC ROCKS, AND THUS TREMOLITE-TALC SCHISTS ARE NOT GENERALLY CONSIDERED AS 'AMPHIBOLITES'. |
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