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Key Characteristics: Two cleavages intersecting at 87 °, moderate birefringence and inclined extinction are key features 2V: 2Vz = 25 - 70° Relief: High positive relief Cleavage: Cleavages intersect at 87 ° Colour and Plechroism: Grains generally…

Key Characteristics: Moderate to high relief, lack of color, low birefringence and uniaxial character are key features 2V: n/a Relief: Moderate to high positive relief Cleavage: Not observed in thin section Colour and Plechroism: Most commonly…

Mineralogical Composition: Dull luster; breaks into hard flat sheets along the slaty cleavage Texture (grain size, shape, sorting): Fine grained; Foliated Metamorphic grade: Low Precursor rock: Mudstone or shale Commercial applications: Roofing…

Key Characteristics: Relief which changes upon rotation of stage, extreme birefringence, rhombohedral cleavage and lamellar twinning are all diagnostic 2V: n/a Relief: Moderate negative to high positive relief; Relief changes upon rotation of stage…

Common Forms/Occurrences: Mainly of sedimentary origin Useful Identification Test: May be attracted to a magnet after heating Chemical formula: Fe2O3 Crystal System: Thin tabular crystals or massive Colour: Silvery gray, black, or brick red Streak:…

Key Characteristics: Two cleavages intersecting at 87 °, moderate birefringence and inclined extinction are key features 2V: 2Vz = 25 - 70° Relief: High positive relief Cleavage: Cleavages intersect at 87 ° Colour and Plechroism: Grains generally…

Common Forms/Occurrences: Always of secondary origin resulting from the alteration of other ores or minerals containing iron Useful Identification Test: Hard or soft; Chemical formula: Fe2O3 ? nH2O Crystal System: Amorphous masses Colour: Yellow…

Common Forms/Occurrences: Occurs in large masses in veins and pegmatites Useful Identification Test: Insoluble in acids except HF; soluble in molten Na2CO3 Chemical formula: SiO2 Crystal System: Hexagonal prism and pyramids Colour: Usually…

Head up at mineral lick

Key Characteristics: The mineral's lack of color, bird's eye extinction and high birefringence are all diagnostic; Talc is very similar to muscovite and is best distinguished by from muscovite by mineral association 2V: 2Vx = 0-30° Relief…

Key Characteristics: Low negative relief, inclined extinction, low birefringence are key features 2V: 2Vz = 58° Relief: Low negative relief Cleavage: Two cleavages intersect at 42° and 138° Colour and Plechroism: Colorless in thin section Optical…

Mineralogical Composition: Calcite (or dolomite) crystals of nearly equal size and tightly fused together; calcite effervesces in dilute HCl; dolomite effervesces only if powdered Texture (grain size, shape, sorting): Fine to coarse grained;…

Common Forms/Occurrences: Found in sedimentary strata; Formed secondarily from limestone Useful Identification Test: Will not effervesce in cold dilute acids; Powdered dolomite will however effervesce in warm acids Chemical formula: CaMg(CO3)2…

Mineralogical Composition: Mafic; Plagioclase Feldspar, Olivine, Pyroxene, Amphibole Texture (extrusive/intrusive): Intrusive; Phaneritic: coarse-grained Other distinctive properties: Dark gray to black; Essential part of oceanic crust

Key Characteristics: The mineral's high relief, strong pleochroism, form and uniaxial character are diagnostic 2V: n/a Relief: Moderate to high positive relief Cleavage: Cleavage not visible in thin section; Grains are commonly fractured Colour…

Common Forms/Occurrences: Principally occurs in metamorphic rocks ie. Crystalline limestones, schists, and gneisses or in hydrothermal veins Useful Identification Test: Opaque, relatively soft, non magnetic, and foliated Chemical formula: C Crystal…

Common Forms/Occurrences: Widely distributed as accessory mineral (all classes of rocks) Useful Identification Test: Soluble in HNO3 or HCl Chemical formula: Ca5F(PO4)3 Crystal System: Hexagonal prisms Colour: Pale green or dark green, brown, blue,…

Common Forms/Occurrences: Found in limestone, chalk, travertine, and onyx Useful Identification Test: Effervesces in dilute HCl Chemical formula: CaCO3 Crystal System: Prisms, rhombohedrons, or scalenohedrons that break into rhombohedrons Colour:…

Texture (grain size, shape, sorting): Breaks into blocks or layers Composition (detrital, biochemical, chemical): Detrital sediment grains; derived from the mechanical and chemical weathering of continental rocks, which are comprised mostly of…

Common Forms/Occurrences: Occurs as extensive beds and irregular masses formed by evaporation of enclosed bodies of sea water Useful Identification Test: Salty taste; Chemical formula: NaCl Crystal System: Forms cubes and octahedrons Colour:…

Texture (grain size, shape, sorting): Mostly sand-sized shell fragments; often contains a few larger whole fossil shells Composition (detrital, biochemical, chemical): Biochemical sediment grains; shells and shell/coral fragments, and/or calcareous…

Texture (grain size, shape, sorting): Fissile (splits easily into layers); no visible grains Composition (detrital, biochemical, chemical): Detrital sediment grains; derived from the mechanical and chemical weathering of continental rocks, which are…

Mineralogical Composition: Quartz sand grains fused together; grains will not rub off like sandstone, usually light colored Texture (grain size, shape, sorting): Fine to coarse grained; Nonfoliated Metamorphic grade: High Precursor rock: Sandstone…

Common Forms/Occurrences: Found as blocky crystals in basalts, gabbro, and andesites Useful Identification Test: Insoluble in HCl Chemical formula: calcium ferromagnesian silicate Crystal System: Short, 8-sided prisms Colour: Dark green to gray…

Key Characteristics: Low relief, colorless nature, polysynthetic twinning and oscillatory zoning are diagnostic of plagioclase 2V: 2Vx = 45 - 102° Relief: Low negative or positive relief Cleavage: Cleavages intersect at 93 °, usually not observed in…