updated 10/06
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| Metallic | H<2.5 | H 2.5 to 3.5 | H 3.5 to 5.5 | H >5.5 | Glossary | Tests | Index |
| STREAK | HARD | COLOR | REMARKS | NAME |
| Black | 1 | Steel gray | S.G. 2.0 Basal cleavage; Soft, marks on paper, greasy feel. Used in lubricants, and as the "lead" in pencils. |
GRAPHITE |
| Iron-black | 1-2 | Black | S.G. 4.8 Radiating fibers, granular masses, or dendritic; sooty. An ore of manganese. |
PYROLUSITE |
| Yellow brown | 1 to 5 | Yellow brown to black | S.G. 3.3 to 4.0 Your basic rust, limonite forms whenever and wherever iron is exposed to oxygen. Many forms and lusters. Occurs as flattened crystals, massive, reniform, or stalactitic. Common secondary mineral in rocks and soils. An important ore of iron. |
LIMONITE |
| Red brown to Indian red | 1 to 6.5 | Steel gray | S.G. 4.8 to 5.3 Many forms and lusters (can also occur in sub-metallic to non-metallic forms). Can be massive, radiating, botryoidal, and micaceous. The crystalline (metallic and sub-metallic) varieties are generally harder than the earthy (non-metallic) varieties. An important ore of iron. |
HEMATITE |
| Gray | 2.5 | Gray | S.G. 7.6 Perfect cubic cleavage (3 @ 90°); Occurs in cubes; may be massive or granular; feels heavy. The most common ore of lead. |
GALENA |
| Light gray to silver | 2.5 | Silvery white, tarnishes to black | S.G. 10 to 12 Hackly fracture, easily distinguished from galena by lack of cleavage. Malleable and ductile. Used in coinage, fillings for teeth, jewelry, silverplate, photography, wires. |
SILVER |
| Yellow | 2.5 to 3.0 | Pale to golden yellow | S.G. 19.3 Hackly fracture. Malleable and ductile. Used in coinage, fillings for teeth, jewelry, goldplate. Extensive use in computer industry as non-corrosive contact points for silicon chips. |
GOLD |
| Gray to black | 3.0 | Bronze, tarnishes to dark blue and purple | S.G. 4.9 to 5.4 Commonly called "peacock ore" because of the purple shine when it tarnishes. A common source of copper. |
BOURNITE |
| Copper red | 3.0 | Copper red | S.G. 8.5 to 9.0 Malleable and ductile. Used in coins, pipes, wires, gutters, cooking utensils, pots and pans, jewelry, decorative items. |
COPPER |
| Greenish-black | 4 | Brass yellow | S.G. 4.3 The distinctive buttery yellow color is often tarnished purple or gray; more yellow and softer than pyrite. An ore of copper. |
CHALCO-PYRITE |
| Chocolate brown | 5.5 | Black to dark brown | S.G. 4.6 Distinctive chocolate brown streak. Commonly occurs as stratabound deposits in dunite segregations in ultramafic rocks, and as podiform masses in serpentinite. Used in stainless steel, high temperature alloys, and as refractory bricks. The ore of chromium. |
CHROMITE |
| Black | 6 | Black | S.G. 5.2 Conchoidal fracture. Strongly magnetic. Often called "lodestone." Common accessory mineral occurring as disseminated grains in mafic igneous rocks. An ore of iron. |
MAGNETITE |
| Black to greenish | 6 | Pale brass | S.G. 5.0 Often in cubic crystals. Can be massive, granular. Common name: "Fool's gold." Commonly alters to limonite. Sometimes mined as a source of sulfur. |
PYRITE |
| STREAK | HARD | COLOR | REMARKS | NAME |
| Yellow-brown | 1 to 5.5 | Yellow to dark brown | S.G. 3.3 to 4.0 Your basic rust, limonite forms whenever and wherever iron is exposed to oxygen. Many forms and lusters. Occurs as flattened crystals, massive, reniform, or stalactitic. Common secondary mineral in rocks and soils. An important ore of iron. |
LIMONITE |
| Red brown to Indian red | 1 to 6.5 | Red, vermillion | S.G. 4.8 to 5.3 Many forms and lusters (can also occur in sub-metallic to non-metallic forms). Can be massive, radiating, botryoidal, and micaceous. The crystalline (metallic and sub-metallic) varieties are generally harder than the earthy (non-metallic) varieties. An important ore of iron. |
HEMATITE |
| Metallic | H<2.5 | H 2.5 to 3.5 | H 3.5 to 5.5 | H >5.5 | Glossary | Tests | Index |
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