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Home , Lustre (mineralogy)

GUIA DE IDENTIFICACIÓN DE MINERALES

Lustre: metálico / submetálico / no metálico Lustre Metálico Generalmente con raya de color, opacos

RAYA DUREZA COLOR REMARKS NOMBRE S.G. 2.0 Steel Black 1 Basal ; Soft, marks on paper, greasy feel. gray GRAFITO Used in lubricants and pencils. S.G. 4.8 Iron-black 1-2 Black Radiating fibers, granular masses, or dendritic; sooty. PYROLUSITA An ore of manganese. S.G. 3.3 to 4.0 Yellow Your basic rust. Many forms and lusters. Occurs as Yellow 1 to 5 brown to flattened , massive, reniform, or stalactitic. brown LIMONITA black Common secondary in rocks and soils. An ore of iron. S.G. 4.8 to 5.3 Many forms and lusters (can also occur in sub- Red metallic to non-metallic forms). Can be massive, Steel brown to 1 to 6.5 radiating, botryoidal, and micaceous. The crystalline gray HEMATITA Indian red (metallic and sub-metallic) varieties are generally harder than the earthy (non-metallic) varieties. An ore of iron. S.G. 7.6 Perfect cubic cleavage (3 @ 90°); Occurs in cubes; Gray 2.5 Gray may be massive or granular; heavy. The most common ore of lead. S.G. 10 to 12 Silvery Hackly , easily distinguished from galena by Light gray white, SILVER 2.5 lack of cleavage. Malleable and ductile. Used in to silver tarnishes PLATA coinage, fillings for teeth, jewelry, silverplate, to black photography, wires. S.G. 19.3 Pale to Hackly fracture. Malleable and ductile. Used in GOLD Yellow 2.5 to 3.0 golden coinage, fillings for teeth, jewelry, goldplate. ORO yellow Extensive use in computer industry as non-corrosive contact points for chips. Bronze, S.G. 4.9 to 5.4 tarnishes Commonly called "peacock ore" because of the Gray to BOURNITE 3.0 to dark purple shine when it tarnishes. black BOURNITA blue and A common source of copper. purple S.G. 8.5 to 9.0 Copper Copper Malleable and ductile. Used in coins, pipes, wires, KOPER 3.0 red red gutters, cooking utensils, pots and pans, jewelry, COBRE decorative items. Greenish- 4 Brass S.G. 4.3 black yellow The distinctive buttery yellow color is often tarnished CALCOPIRITA purple or gray; yellower and softer than . An ore of copper. S.G. 4.6 Distinctive chocolate brown . Commonly occurs Black to as stratabound deposits in dunite segregations in Chocolate 5.5 dark ultramafic rocks, and as podiform masses in brown brown serpentinite. Used in stainless steel, high CROMITA temperature alloys, and as refractory bricks. The ore of . S.G. 5.2 Conchoidal fracture. Strongly magnetic. Often called Black 6 Black "lodestone." Common accessory mineral occurring as MAGNETITA disseminated grains in mafic igneous rocks. An ore of iron. S.G. 5.0 Often in cubic crystals. Can be massive, granular. Black to Pale PYRITE 6 Common name: "Fool's gold." Commonly alters to greenish brass PIRITA limonite. Sometimes mined as a source of sulfur.

LUSTRE: Sub metálico

RAYA DUREZA COLOR REMARKS NOMBRE S.G. 3.3 to 4.0. Your basic rust. Many forms and lusters. Occurs as Yellow- Yellow to LIMONITE 1 to 5.5 flattened crystals, massive, reniform, or stalactitic. brown dark brown LIMONITA Common secondary mineral in rocks and soils. An ore of iron. S.G. 4.8 to 5.3 Many forms and lusters (can also occur in sub-metallic Red to non-metallic forms). Can be massive, radiating, brown to Red, HEMATITE 1 to 6.5 botryoidal, and micaceous. The crystalline (metallic Indian HEMATITA vermillion and sub-metallic) varieties are generally harder than red the earthy (non-metallic) varieties. An ore of iron.

LUSTRE: No-metálico. Raya incolora o de color muy claro Dureza: < 2.5 / 2.5 a 3.5 / 3.5 a 5.5 / >5.5

Dureza: < 2.5 (se marca con la uña del pulgar)

PATRON D SP. DUREZA COLOR REMARKS NOMBRE RUPTURA GR. Easily scratched with fingernail. Flexible but not elastic; foliated; slick or soapy feeling. Typical luster: Good White, pearly to waxy. Used on baby's butts, 1 cleavage in green, 2.7 and in paints, ceramics, rubber, TALCO 1 direction pink insecticides, and paper. Variety SOAPSTONE can be carved into ornamental shapes and items. Earthy; clayey odor. Earthy to dull luster. A swelling clay, used to stop MONTMOR- White, leaks in soils, rocks, dams, and 1-2 Fracture 2-3 ILLONITE tan, gray basement walls. Due to its excellent MONTMORILONITA water-retention properties, it is also used as a soil additive and kitty litter. Not truly a mineral (lacks fixed Yellow chemical composition). Earthy to Uneven BAUXITE 1-3 brown to 2-3 pisolitic (large round grains). Earthy, fracture BAUXITA red dull to waxy lusters. The most important ore of aluminum. Your basic rust. Many forms and Yellow, lusters. Occurs as flattened crystals, Conchoidal 2.7- LIMONITE 1-5.5 brown to massive, reniform, or stalactitic. fracture 4.3 LIMONITA black Common secondary mineral in rocks and soils. An ore of iron. Many forms and lusters (can also occur in metallic forms). Can be massive, radiating, botryoidal, and Brown, 4.8 Irregular micaceous. The crystalline (metallic HEMATITE 1-6 red, steel to fracture and sub-metallic) varieties are HEMATITA gray 5.3 generally harder than the earthy (non-metallic) varieties. An ore of iron. Characteristic bright yellow color; when small pieces are held in the hand close to the ear, crackling can Conchoidal be heard due to rapid, uneven SULFUR 1.5-2.5 to uneven Yellow 2.1 thermal expansion. Pearly, waxy, AZUFRE fracture resinous, to dull lusters. Used to make sulfuric acid, fertilizers, insecticides, explosives (kaBoom), and medicines. 2 No White, 2.6 Earthy; clayey odor; absorbs macroscopic often moisture so rapidly that it will stick to KAOLINITA cleavage colored by the tongue. Earthy to dull lusters. impurities Used in refractories, china, pottery and as a filler in paper. Also used in soft-serve ice cream to retard melting on hot summer days. As crystals and broad cleavage flakes with waxy to pearly to vitreous Colorless, lusters ( variety); as compact white, fine-grained masses showing no 1 direction, gray, visible cleavage, earthy to dull to perfect, 2 2 gray- 2.3 waxy lusters (alabaster variety); as directions, YESO brown, fibers with satiny luster (satin spar good pink variety). Large crystals somewhat reddish flexible, but not elastic. Used to make Plaster of Paris and sheetrock wallboard (drywall). Thin sheets are flexible, but not elastic. Lusters typically resinous, waxy, vitreous or dull. A common Dark alteration mineral found in mafic CHLORITE green to 2-2.5 1 direction 2.7 igneous rocks (alteration of the green- ferromagnesian to chlorite black CLORITA results in the greenish tint common to altered basalt, and the re-naming of the "greenstone." Platy or fibrous; waxy luster when Wavy, massive, satiny luster when fibrous Green SERPENTINE 2-3 uneven 2.5 ( variety). Used as an and white SERPENTINITA fracture insulating material against heat and electricity. In granular cleavable masses or cubic crystals. Soluble in water; salty White taste. Typical lusters: vitreous, waxy, 3 directions, when 2.1 dull. Common salt: used as a source 2.5 perfect, pure; may to of sodium compounds and HALITA cubic be red, 2.3 hydrochloric acid; used to salt blue, pink highways in winter; used as a seasoning and preservative in food. Common silicate mineral in felsic igneous rocks and low to medium grade metamorphic rocks. In foliated masses and scales. Transparent, flexible and elastic sheets. Vitreous Pale to pearly luster. Used as insulating 1 direction brown, material in electrical appliances and 2.5 2.8 perfect green, as a fireproofing material. Also, MUSCOVITA yellow Muscovite was used as windows before the invention of plate glass, was common as the rear window in early model convertible cars, and is still used as the front view-screen in many "fire-view" type wood stoves. Common ferromagnesian silicate mineral in felsic to intermediate Dark igneous rocks and low to medium 1 direction, brown, grade metamorphic rocks. In MICA 2.5 to 3.0 3.0 perfect green to irregular foliated masses and scales. black Translucent, somewhat flexible and BIOTITA elastic sheets. Pearly to vitreous luster. Forms hexagonal crystals.

LUSTRE: No-metálico Raya Incolora o de Color Claro Dureza: 2.5 a 3.5 (no se puede marcar con uña ni con moneda de cobre)

PATRON D SP. DUREZA COLOR REMARKS NOMBRE RUPTURA GR. Your basic rust. Many forms and lusters. Yellow, Occurs as flattened crystals, massive, Conchoidal 2.7- LIMONITE 1-5.5 brown to reniform, or stalactitic. Common fracture 4.3 LIMONITA black secondary mineral in rocks and soils. An ore of iron. Many forms and lusters (can also occur in metallic forms). Can be massive, 4.8 radiating, botryoidal, and micaceous. The Irregular Brown, red, HEMATITE 1-6 to crystalline (metallic and sub-metallic) fracture steel gray HEMATITA 5.3 varieties are generally harder than the earthy (non-metallic) varieties. An ore of iron. Platy or fibrous; waxy luster when Wavy, Green and massive, satiny luster when fibrous SERPENTINE 2-3 uneven 2.5 white (asbestos variety). Used as an insulating SERPENTINITA fracture material against heat and electricity. In granular cleavable masses or cubic crystals. Soluble in water; salty taste. White Typical lusters: vitreous, waxy, dull. 3 directions, when pure; 2.1 Common salt: used as a source of HALITE 2.5 perfect, may be to sodium compounds and hydrochloric HALITA cubic red, blue, 2.3 acid; used to salt highways in winter; pink used as a seasoning and preservative in food. Common silicate mineral in felsic igneous rocks and low to medium grade metamorphic rocks. In foliated masses and scales. Transparent, flexible and Pale elastic sheets. Vitreous to pearly luster. MUSCOVITE 1 direction brown, Used as insulating material in electrical 2.5 2.8 MICA perfect green, appliances and as a fireproofing material. MUSCOVITA yellow Also, Muscovite was used as windows before the invention of plate glass, was common as the rear window in early model convertible cars, and is still used as the front view-screen in many "fire- view" type wood stoves.

Common ferromagnesian silicate mineral in felsic to intermediate igneous rocks and Dark BIOTITE low to medium grade metamorphic rocks. 1 direction, brown, MICA 2.5 to 3.0 3.0 In irregular foliated masses and scales. perfect green to Translucent, somewhat flexible and black elastic sheets. Pearly to vitreous luster. BIOTITA Forms hexagonal crystals. Crystals in many forms. Occurs as large granular masses (limestone and marble) Clear, and fine granular or fibrous masses in translucent, 3 directions, which cleavage not prominent; also dark 2.5 to 3.0 perfect 2.7 compact masses. Effervesces in cold, brown, @75° dilute HCl. Typical lusters: vitreous, green to CALCITA pearly, waxy. Used in manufacture of black cement, crushed stone, and as agricultural lime. Crystals usually tabular or bladed. Barite's distinctive characteristic is its specific gravity, which is very high for a 1 direction, nonmetallic mineral. Typical lusters: BARITE perfect, 2 White or 3 to 3.5 4.5 vitreous, pearly to dull. Used in powder directions, gray form to give weight to drilling muds in good BARITA order to prevent "blow-outs" of oil and gas wells, and to maintain the stability of the hole in core and rotary drilling.

LUSTRE: No-metálico Raya Incolora o de Color Claro Dureza: 3.5 a 5.5 (se marca con moneda cobre pero no con vidrio/navaja)

PATRON D SP. DUREZA COLOR REMARKS NOMBRE RUPTURA GR. Your basic rust. Many forms and lusters. Yellow, Conchoidal 2.7- Occurs as flattened crystals, massive, reniform, LIMONITE 1-5.5 brown to fracture 4.3 or stalactitic. Common secondary mineral in LIMONITA black rocks and soils. An ore of iron. Many forms and lusters (can also occur in Brown, metallic forms). Can be massive, radiating, 4.8 Irregular red, botryoidal, and micaceous. The crystalline HEMATITE 1-6 to fracture steel (metallic and sub-metallic) varieties are HEMATITA 5.3 gray generally harder than the earthy (non-metallic) varieties. An ore of iron. Usually harder than a penny. As crystals with White, curved faces (twisted rhombs), and as granular 3 directions, pink, masses (dolostone, dolomitic marble). 3.5 to 4.0 perfect at brown, 2.9 Effervesces in cold, dilute HCl only if DOLOMITA 75° gray, powdered. Typical lusters: vitreous, pearly, etc. waxy. Used as a building and decorative stone. Yellow Usually massive. All six cleavages rarely seen to on a single specimen. Luster typically resinous, Perfect brown, but may be adamantine on well developed 3.5 to 4.0 cleavage in 4 black, crystals. The most important ore of zinc. 6 directions reddish ESFALERITA brown As crystals with curved faces; usually Light to 3 directions, cleavable; sometimes in granular masses. dark 3.5 to 4.0 perfect, 4 Effervesces in dilute HCl only if powdered. brown; rhombic Typical lusters: vitreous, pearly, waxy. A minor maroon SIDERITA ore of iron. Well-formed cubic crystals, and also massive. Purple, Typical lusters: vitreous, pearly. Used in Good in 4 green to production of hydrofluoric acid, and as a flux in 4.0 directions, 3.2 yellow, steel making. The fluorine used in fluoridation octahedral colorless of public drinking water supplies and FLUORITA toothpastes comes from fluorite. Massive and granular. Vitreous luster when i large crystals; earthy luster when in fine- Poor Green to grained earthy masses. High quality crystals 5.0 cleavage, 1 3.2 brown are used as semiprecious . Most direction important use is as source of phosphate for APATITO fertilizers. Crystals slender, fibrous. Often look like long, 2 directions, skinny rods. Commonly occur in cleavage AMPHIBOLE 3.0 good, at Black to fragments or granular masses. Typical lusters; GROUP 5.0 to 6.0 to approx. 60° green vitreous to dull. is a common 3.3 and 120° ferromagnesian mineral in intermediate silicate ANFIBOL rocks (granitic to dioritic composition). In bladed aggregates. Cleavage parallel to length of crystals. Hardness variable. Typical Good in 1 Blue to 5.0 to 7.0 3.6 lusters: vitreous, pearly, dull. Used in direction green manufacture of spark plugs and other high refractory porcelains. Crystals "stubby" with nearly rectangular cross 2 directions, PYROXENE 3.1 section. Commonly in granular or crystalline poor to fair, Green to GROUP 5.5 to 6.0 to masses. Typical lusters: vitreous to dull. at approx. black 3.5 Common ferromagnesian mineral in mafic to 90° ultramafic silicate rocks. PIROXENO

LUSTRE: No-metálico Raya Incolora o de Color Claro Dureza: >5.5 (se marca con un vidrio/navaja)

BREAKAGE SP. HARD COLOR REMARKS NAME PATTERN GR. Crystals slender, fibrous. Often look like long, 2 directions, skinny rods. Commonly occur in cleavage 3.0 AMPHIBOLE 5.0 to good at Black to fragments or granular masses. Typical lusters; to GROUP 6.0 approx. 60° green vitreous to dull. HORNBLENDE is a common 3.3 ANFIBOL and 120° ferromagnesian mineral in intermediate silicate rocks (granitic to dioritic composition). In bladed aggregates. Cleavage parallel to length of crystals. Hardness variable. Typical KYANITE 5.0 to Good in 1 Blue to 3.6 lusters: vitreous, pearly, dull. Used in the 7.0 direction green manufacture of spark plugs and other high CIANITA refractory porcelains. Crystals "stubby" with nearly rectangular 2 directions, PYROXENE 3.1 cross section. Commonly in granular or 5.5 to poor to fair Green to GROUP to crystalline masses. Typical lusters: vitreous to 6.0 at approx. black 3.5 dull. A common ferromagnesian mineral in 90° mafic to ultramafic silicate rocks. PIROXENO As cleavable masses or irregular grains in Colorless, rocks; as crystals in pegmatites and some white, igneous bodies. Luster generally vitreous to 2.5 GROUP 2 directions, pink, red, pearly. Used in manufacture of some 6.0 to good at 90° gray, porcelains. Orthoclase is the common 2.6 green, feldspar found in felsic silicate rocks. ORTOCLASA Gpo blue Common varieties include FELDESPATO (pink), and (blue). In cleavable masses or irregular grains. Striations common on cleavage planes. Luster generally vitreous to pearly. Used in Colorless, 2.6 manufacture of some ceramics. Forms a FELDSPAR GROUP 2 directions, white, 6.0 to continuous series from the calcium rich variety good at 86° gray to 2.8 to the sodium-rich variety (refer to Bowen's black PLAGIOCLASA Reaction Series). Plagioclase is the common Gpo.FELDESPATO feldspar found in intermediate to mafic silicate rocks. Usually in 12 or 24 sided crystals (commonly as porphyroblasts in schists): also massive. Uneven Red to No cleavage, but some samples may exhibit 6.5 4.3 fracture brown parting. Typical lusters: resinous, vitreous, dull. Used as an abrasive: well formed GRANATE crystals may be used as gemstones. Usually as disseminated grains in mafic igneous rocks; as granular masses having Olive 3.3 saccharoidal texture (looks like grains of 6.5 to Conchoidal green to to sugar). Luster generally vitreous. Mined for 7.0 fracture yellow 3.4 refractory sand used in casting industry. A green OLIVINO common ferromagnesian mineral in mafic to ultramafic silicate rocks. As crystals with hexagonal cross section, often with striations on prism faces. Also as crystalline masses, granular aggregates, Colorless irregular grains, etc. Luster generally vitreous or white to greasy. Varieties include MILKY (white to Conchoidal when 7.0 2.6 cloudy, usually due to included microscopic fracture pure, but air bubbles); SMOKEY (gray to black); ROSE may be CUARZO (pink); (violet). Used as a any color , to make glass, as a source of silicon for the computer industry, a flux, a filler, and an abrasive. Translucent to opaque. Varieties include (massive to banded, many colors); MICRO- FLINT (dark gray to blue); CHERT (light- CRYSTALLINE colored, white to gray); (commonly Conchoidal Various QUARTZ 7.0 2.6 red but can include many hues); (milk- fracture colors white, yellow, green, red, multi hued with "fire," waxy luster); (brown to CUARZO gray, fibrous to botryoidal). Agate and opal MICROCRISTALINO are used as gemstones. Usually in trigonal prismatic crystals with prominent lengthwise-running striations. Cleavage Varied; 7.0 to Typical lusters: vitreous to dull. Well-formed not black 3.2 7.5 and colored crystals used as gemstones. prominent common Commonly occur in prgmatite dikes, and in TURMALINA higher grade metamorphic rocks. Cruciform twin crystals common; also Red- elongate bladed crystals with rhombic cross Cleavage 7.0 to brown to sections. Luster resinous to vitreous when not 3.7 7.5 brownish- unaltered; dull to earthy when altered or prominent black impure. Well-formed, cross-shaped twins ESTAUROLITA used in jewelry ("Fairy Crosses").

Hexagonal, prismatic crystals. Luster Imperfect Green to generally vitreous. Used as a source of 8.0 2.7 cleavage yellow beryllium for metal alloys. High quality crystals used as gemstomes. BERILO Colorless, Prismatic crystals, crystalline or granular 1 direction, 8.0 pink, 3.5 masses. Luster generally vitreous. High poor yellow quality crystals used as gemstone. TOPACIO Crystals generally hexagonal prisms, commonly barrel-shaped. Basal parting Parting, no Brown, common. Typical lusters: vitreous to dull. 9.0 true pink, 4.0 Used as an abrasive; high quality, colored cleavage -red CORUNDO crystals used as gemstones: RUBY (red), /CORINDON (blue). Uncut crystals have a characteristic greasy Colorless, appearance; well-formed crystals are DIAMOND 10 4 directions pale 3.5 octahedral. Luster: adamantine. Industrial yellow (borts) used as abrasives; high DIAMANTE quality diamonds used as gemstones. GRUPO DEL FELDESPATO

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