Search Islandora Content

Common Forms/Occurrences: Found near hot springs and volcanic regions Useful Identification Test: Identifiable odour when mixed with water (resembles rotton eggs) Chemical formula: S Crystal System: Transparent to translucent crystals or earthy…

Common Forms/Occurrences: In veins associated with other sulfide minerals Useful Identification Test: Decomposed by H2SO4 and by dilute HNO3 Chemical formula: PbS Crystal System: Forms cubes and octahedrons Colour: Silvery gray Streak: Gray to dark…

Key Characteristics: Strong coloration and pleochroism, 2 intersecting cleavages, and diamond shaped basal sections are diagnostic 2V: 2Vx = 35 - 130° Relief: Moderate to high positive relief Cleavage: Two cleavages intersect at 56 ° and 124 °.…

Common Forms/Occurrences: Found in hydrothermal deposits Useful Identification Test: Insoluble in HCl; When powdered soluble in strong HNO3 Chemical formula: FeS2 Crystal System: Cubes and octahedrons Colour: Brass yellow Streak: Dark gray Lustre:…

Common Forms/Occurrences: Secondary mineral formed by alteration of magnesium silicates (ie. Olivine and pyroxene) Useful Identification Test: Very soft to the touch, soapy feel Chemical formula: Mg3Si4O10(OH)2 Crystal System: Cryptocrystalline…

Common Forms/Occurrences: Found in alabaster, satin spar, and selenite Useful Identification Test: Soft; Shows better cleavage than talc Chemical formula: CaSO4 ? 2H20 Crystal System: Tabular crystals, prisms, blades, or needles Colour: Colourless,…

Common Forms/Occurrences: Common constituent of Precambrian iron-formations Useful Identification Test: Attracted to a magnet and can be magnetized Chemical formula: Fe3O4 Crystal System: Octahedrons Colour: Silvery gray to black Streak: Dark gray…

Key Characteristics: Relief which changes upon rotation of stage, extreme δ, rhombohedral cleavage and lamellar twinning are all diagnostic. Dolomite usually has higher refractive indices than calcite and may be colorless or iron stained where…

Key Characteristics: Strong brown coloration and plechroism, birds eye and parallel extinction, and high birefringence are diagnostic 2V: 2Vx = 0 - 25° Relief: moderately high positive relief Cleavage: One perfect cleavage Colour and Plechroism:…

Common Forms/Occurrences: Associated with galena and in hydrothermal veins in igneous rocks and contact metamorphic deposits Useful Identification Test: Soluble in HCl with evolution of H2S Chemical formula: ZnS Crystal System: Misshapen…

Common Forms/Occurrences: Two groups classified as Pyralspite and Ugrandite Useful Identification Test: Soluble with difficulty in HF Chemical formula: complex silicate Crystal System: Dodecahedrons Colour: Usually red, black, or brown; sometimes…

Common Forms/Occurrences: Igneous and metamorphic rocks Useful Identification Test: Lack of colour, low relief, and albite twinning Chemical formula: NaAlSi3O8 to CaAl2Si2O8 Crystal System: Striated tabular crystals or blades Colour: Colourless,…

Common Forms/Occurrences: Found in granites and pegmatites Useful Identification Test: Can be split into thin flexible transparent sheets Chemical formula: KAl2(Al,Si3O10)(OH,F)2 Crystal System: Short opaque prisms Colour: Colourless, yellow, brown…

Key Characteristics: The mineral's low relief, lack of color and tartan twinning are characteristic. In plagioclase feldspar polysynthetic twinning in two directions can mimic microcline's tartan twinning. However, the polysynthetic…

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…

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…

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…

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…

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…