Part 20

+-----------------+-----------------------+--------------+-------------+ |=Name of Mineral=| =Crystallization and | =Tenacity |=Diaphaneity=| | | Occurrence= | etc.= | | +-----------------+-----------------------+--------------+-------------+ |=Amphibole.= |Prismatic crystals with|Brittle to |Opaque to | | |hexagonal cross-sec- |tough. |transparent. | | |tion, common; also | | | | |cleavable masses. | | | | | | | | |=Arsenopyrite.= |Crystals resemble a |Brittle. |Opaque. | | |double-edged axe. | | | | |Occurs also coarse to | | | | |fine granular. | | | | | | | | |=Barite.= |Diamond shaped or rect-|Brittle. |Transparent | | |angular tabular, or | |to | | |prismatic crystals and | |translucent. | | |platy masses. | | | | | | | | |=Biotite.= |Six-sided tabular crys-|Flexible and |Opaque to | | |tals, and as scales, |elastic. |transparent. | | |plates, or scaly | | | | |masses. | | | | | | | | |=Calcite.= |Prismatic or tabular |Brittle. |Transparent | | |six-sided crystals; | |to opaque. | | |also granular, | | | | |cleavable, or earthy | | | | |masses. | | | | | | | | |=Chalcocite.= |Usually very compact |Slightly |Opaque. | | |masses; six-sided, |sectile. | | | |tabular crystals rare. | | | | | | | | |=Chalcopyrite.= |Occurs massive or in |Brittle. |Opaque. | | |scattered particles. | | | | |Crystals usually have | | | | |four triangular faces. | | | | | | | | |=Copper.= |Masses, plates, scales,|Malleable |Opaque. | | |branching aggregates |sectile. | | | |and octahedral crys- | | | | |tals, usually | | | | |distorted. | | | | | | | | |=Corundum.= |Prismatic or tabular |Brittle to |Translucent | | |six-sided crystals; |tough. |to | | |also granular and | |transparent. | | |pseudo-cleavable | | | | |masses. | | | | | | | | |=Epidote.= |Slender, deeply grooved|Brittle. |Transparent | | |prismatic crystals and | |to opaque. | | |cleavable to fine | | | | |granular masses. | | | | | | | | |=Fluorite.= |In groups of crystals, |Brittle. |Transparent | | |usually cubical; also | |to | | |in cleavable masses. | |translucent. | | |Sometimes granular. | | | | | | | | |=Galenite.= |Cubical crystals, often|Very Brittle. |Opaque. | | |with triangular faces | | | | |on the corners; also, | | | | |cleavable to granular | | | | |masses. | | | | | | | | |=Garnet.= |Complex, rounded crys- |Brittle. |Transparent | | |tals, glassy masses and| |to opaque. | | |granular. | | | | | | | | |=Gold.= |Nuggets, plates, |Malleable |Opaque. | | |scales, wires; |sectile. | | | |branching aggregates | | | | |and distorted crystals,| | | | |usually octahedral. | | | | | | | | |=Graphite.= |Imbedded scales and |Sectile |Opaque. | | |foliated, granular or |Flexible. | | | |compact masses. Rarely | | | | |in six-sided, tabular | | | | |crystals. | | | | | | | | |=Gypsum.= |Diamond shaped crys- |Sectile, Thin |Translucent | | |tals, and cleavable, |flakes, |to | | |fibrous, granular, |flexible. |transparent. | | |foliated or compact | | | | |masses. | | | | | | | | |=Halite.= |Cubical or octahedral |Brittle. |Translucent | | |crystals; also | |to | | |cleavable, granular or | |transparent. | | |compact masses. | | | | | | | | |=Hematite.= |Complex, tabular or |Brittle. |Opaque. | | |rounded crystals; also | | | | |platy, oolitic, earthy,| | | | |micaceous, and kidney | | | | |shaped masses. | | | | | | | | |=Limonite.= |Botryoidal or stalac- |Brittle. |Opaque. | | |titic forms with a | | | | |radiating fibrous | | | | |structure and a | | | | |varnish-like surface, | | | | |also earthy masses and | | | | |concretions. | | | | | | | | |=Magnetite.= |Octahedral crystals, |Brittle. |Opaque. | | |and coarse to fine | | | | |granular, laminated, or| | | | |compact masses. | | | | | | | | |=Malachite.= |Massive, as botryoidal |Brittle. |Translucent | | |crusts with a radiating| |to opaque. | | |structure and silky | | | | |lustre, and as slender | | | | |crystals forming | | | | |velvety surfaces. | | | | | | | | |=Muscovite.= |Six-sided, tabular |Flexible and |Transparent | | |crystals, and as |elastic. |to | | |scales, plates, or | |translucent. | | |scaly masses. | | | | | | | | |=Orthoclase.= |Thick-set square or |Brittle. |Transparent | | |six-sided crystals, or | |to opaque. | | |cleavable masses or | | | | |grains. | | | | | | | | |=Pyrite.= |Cubical, octahedral, or|Brittle. |Opaque. | | |complexly rounded crys-| | | | |tals, coarse to fine | | | | |granular, and massive. | | | | | | | | |=Pyrolusite.= |Occurs as radiating |Brittle. |Opaque. | | |prismatic layers, | | | | |velvety crust and | | | | |granular to compact | | | | |masses. Soils the | | | | |fingers. | | | | | | | | |=Pyroxene.= |Prismatic crystals with|Brittle. |Transparent | | |square or octagonal | |to opaque. | | |cross-section; also | | | | |foliated and massive. | | | | | | | | |=Quartz.= (Pheno-|Six-sided prism termi- |Brittle. |Transparent. | |crystalline). |nated by a six-sided | | | | |pyramid; also massive, | | | | |coarse to fine | | | | |granular, and as sand. | | | | | | | | |=Quartz.= (Cryp- |Very fine grained |Brittle. |Translucent | |tocrystalline). |massive, botryoidal, | |to opaque. | | |nodular, or filling or | | | | |lining cavities in | | | | |rocks. | | | | | | | | |=Serpentine.= |Compact, massive or |Tough. Fibres |Translucent | | |coarse to fine fibrous.|are flexible. |to opaque. | | |The two habits are | | | | |often in parallel | | | | |layers. | | | | | | | | |=Siderite.= |Cleavable masses, |Brittle. |Translucent | | |coarse to fine, | |to opaque. | | |granular and at warped | | | | |crystals that resemble | | | | |distorted cubes. | | | | | | | | |=Sphalerite.= |Complexly rounded or |Brittle. |Transparent | | |modified cubical crys- | |to opaque. | | |tals; also cleavable, | | | | |coarse to fine granular| | | | |masses, and botryoidal,| | | | |etc. | | | | | | | | |=Stibnite.= |Sharp, vertically |Very brittle. |Opaque. | | |grooved, prismatic | | | | |crystals and in | | | | |cleavable masses with a| | | | |bladed structure. | | | | | | | | |=Talc.= |Foliated, coarse to |Tough sectile.|Transparent | | |fine granular, or | |to | | |compact masses. Feels | |translucent. | | |greasy to soapy. | | | | | | | | | | | | | |=Tetrahedrite.= |Crystals have four |Brittle. |Opaque. | | |triangular faces. | | | | |Occurs usually granular| | | | |massives. | | | | | | | | |=Tourmaline.= |Vertically lined, |Very brittle. |Transparent | | |prismatic crystals with| |to opaque. | | |spherical triangular | | | | |cross-sections. Also | | | | |columnar or compact | | | | |massive. | | | | | | | | |=Zoisite.= |Occurs in tri-metric |Brittle. |Transparent, | | |crystals; also massive.| |translucent. | +-----------------+-----------------------+--------------+-------------+