| Chart No. | Mineral | [Streak] | Remarks | Hardness |
| 1. | METALLIC luster, WHITE color |
|---|
| | A. | Does not readily leave mark on paper but can be scratched by ordinary pocket knife |
| | | [Native silver] | Shiny silver white, unless tarnished | Silver-white color that tarnishes to gray, black, or yellowish brown; heavy; can be flattened when hit with hammer | 2½-3 |
| 2. | METALLIC or SUBMETALLIC luster, GRAY color |
|---|
| | A. | Will leave mark on paper |
| | | [Argentite] | Shiny, blackish to lead gray | Lead-gray color that tarnishes to dull black; knife cuts it smoothly; heavy; may occur as masses and coatings | 2-2½ |
| | | [Galena] | Grayish black | Shiny lead-gray color; heavy; cube-shaped fragments and crystals | 2½ |
| | | [Graphite] | Black | Steel-gray color; greasy feel; very soft; splits into thin flakes | 1-2 |
| | B. | Does not readily leave mark on paper but can be scratched by ordinary pocket knife |
| | | [Chalcocite] | Grayish black | Shiny lead-gray color that tarnishes to dull black; knife cuts it smoothly; may have black sooty coating; commonly occurs as compact or [granular] masses | 2½-3 |
| | | [Hollandite] | Black | Silvery-gray color; may occur as rounded masses | 4-6 |
| | C. | Cannot be scratched by ordinary pocket knife |
| | | [Braunite] | Steel gray or black | Dark steel-gray color and submetallic luster | 6-6½ |
| | | [Hematite] | Dark reddish brown | Steel-gray color; commonly occurs as granular or compact masses; shiny, scaly variety is specular [hematite]; notice streak | 5½-6½ (may be softer) |
| | | [Hollandite] | Black | Silvery-gray color; may occur as rounded masses | 4-6 |
| 3. | METALLIC luster, YELLOW color |
|---|
| | A. | Does not readily leave mark on paper but can be scratched by ordinary pocket knife |
| | | [Chalcopyrite] | Greenish black | Brass-yellow or golden-yellow color that may tarnish and show rainbow-like colors; commonly [massive]; notice streak | 3½-4 |
| | | [Gold] | Shiny golden yellow | Shiny yellow color; extremely heavy; flattens when hit with hammer; notice streak | 2½-3 |
| | B. | Cannot be scratched by ordinary pocket knife |
| | | [Pyrite] | Black, greenish black, or brownish black | Shiny, pale golden-yellow or brass-yellow color that may tarnish; occurs as grains, as masses, or as [cubes] or other crystal shapes; notice hardness and streak | 6-6½ |
|
| 4. | METALLIC or SUBMETALLIC luster, BROWN color |
|---|
| | A. | Does not readily leave mark on paper but can be scratched by ordinary pocket knife |
| | | [Limonite] | Rusty yellowish brown | Dark-brown color; some specimens have a shiny black surface; notice streak | 5-5½ |
| | B. | Cannot be scratched by an ordinary pocket knife |
| | | [Cassiterite] | Pale brown, pale yellow or white | Brown; submetallic; heavy; notice streak | 6-7 |
| | | [Hematite] | Dark reddish brown | Dark brown color; commonly occurs as granular or compact masses; notice streak | 5½-6½ (may be softer) |
| | | [Limonite] | Rusty, yellowish brown | Dark brown color; some specimens have a shiny black surface; notice streak | 5-5½ |
| 5. | METALLIC or SUBMETALLIC luster, BLACK color |
|---|
| | A. | Will leave mark on paper |
| | | [Argentite] | Shiny, blackish to lead grey | Lead-gray color that tarnishes to dull black; knife cuts it smoothly; heavy; may occur as masses and coatings | 2-2½ |
| | | [Graphite] | Black | Greasy feel; very soft; splits into thin flakes | 1-2 |
| | | [Pyrolusite] | Black | Very soft; will soil fingers; may be powdery | 1-2 |
| | B. | Does not readily leave mark on paper but can be scratched by an ordinary pocket knife |
| | | [Chalcocite] | Grayish black | Shiny lead-gray color that tarnishes to dull black; knife cuts it smoothly; may have a black sooty coating; commonly occurs as compact or granular masses | 2½-3 |
| | | [Hollandite] | Black | May occur as rounded masses | 4-6 |
| | | [Limonite] | Rusty, yellowish brown | Some specimens have shiny black surface; notice streak | 5-5½ |
| | C. | Cannot be scratched by an ordinary pocket knife |
| | | [Braunite] | Steel gray or black | Luster is submetallic | 6-6½ |
| | | [Cassiterite] | Pale brown, pale yellow, or white | Submetallic luster; heavy; notice streak | 6-7 |
| | | [Hematite] | Dark reddish brown | Notice streak; commonly occurs as granular or compact masses | 5½-6½ (may be softer) |
|
| | | [Hollandite] | Black | May occur as rounded masses | 4-6 |
| | | [Limonite] | Rusty yellowish brown | Some specimens have shiny black surface; notice streak | 5-5½ |
| | | [Magnetite] | Black | Fragments cling to a magnet | 6 |
| | | [Pitchblende] | Brownish black | Brownish black, greenish black, or black; radioactive; heavy; may appear dull or greasy | 5½ |
| 6. | NONMETALLIC luster, WHITE color |
|---|
| | A. | Can be scratched by a fingernail |
| | | [Cerargyrite] | Shiny white or gray | Appears waxy; knife cuts it smoothly; turns violet brown to black when exposed to light | 1-1½ |
| | | [Gypsum] | White | Soft; occurs as crystals or as fibrous, granular, compact, or earthy masses | 2 |
| | | [Talc] | White | Knife cuts it smoothly; feels soapy or greasy; splits into thin flakes | 1 |
| | B. | Cannot be scratched by a fingernail but can be scratched by a copper penny |
| | | [Anhydrite] | White | Commonly occurs as sugary-looking masses | 3-3½ |
| | | [Barite] | White | Rather heavy; [cleavage fragments] may be flat and slab-like | 3-3½ |
| | | [Calcite] | White | Dilute hydrochloric acid fizzes on [calcite]; perfect [cleavage] in 3 directions gives rhomb-shaped fragments | 3 |
| | | [Celestite] | White | Not quite as heavy as [barite]; crystals commonly prism-shaped or flat-looking; some cleavage fragments are flat and slab-like | 3-3½ |
| | | [Halite] | White | Salty taste; dissolves in water; cube-shaped cleavage fragments | 2½ |
| | C. | Cannot be scratched by a copper penny but can be scratched by an ordinary pocket knife |
| | | [Anhydrite] | White | Commonly occurs as sugary-looking masses | 3-3½ |
| | | [Barite] | White | Rather heavy; cleavage fragments may be flat and slab-like | 3-3½ |
| | | [Celestite] | White | Not quite as heavy as barite; crystals commonly prism-shaped or flat-looking; some cleavage fragments are flat and slab-like | 3-3½ |
|
| | | [Dolomite] | White | Commonly occurs as granular masses and as rhomb-shaped crystals; dilute hydrochloric acid may fizz slightly on [dolomite] | 3½-4 |
| | | [Fluorite] | White | Cleavage in 4 directions can give fragments that are shaped like [octahedrons]; crystals commonly cubes | 4 |
| | | [Opal] | White | Curved, [conchoidal] [fracture]; may appear glassy, greasy, resinous, or dull; milky white and bluish-white [precious opal] shows plays of colors | 5-6 |
| | D. | Cannot be scratched by an ordinary pocket knife but can be scratched by [quartz] |
| | | [Feldspar] | White | Glassy or pearly luster; good cleavage in 2 directions that meet at an angle of 90° or near 90°; common in [granite] and [pegmatite] rocks | 6 |
| | | [Opal] | White | Curved, conchoidal fracture; may appear glassy, greasy, resinous, or dull; milky white and bluish-white precious opal shows plays of colors | 5-6 |
| | | [Quartz] | White | Curved conchoidal fracture; occurs as [milky quartz], [chert], and [chalcedony]; crystals commonly 6-sided prisms with pyramid-like ends | 7 |
| 7. | NONMETALLIC luster, GRAY color |
|---|
| | A. | Can be scratched by a fingernail |
| | | [Amphibole asbestos] | White | Made up of slender, flexible fibers that can be pulled apart | 1-2½ |
| | | [Cerargyrite] | Shiny white or gray | Appears waxy; knife cuts it smoothly; turns violet brown to black when exposed to light | 1-1½ |
| | | [Gypsum] | White | Soft; occurs as crystals or as fibrous, granular, compact, or earthy masses | 2 |
| | | [Sulfur] | White or pale yellow | Will burn with a blue flame; commonly found as crystals, crusts, or grains | 1½-2½ |
| | | [Talc] | White | Knife cuts it smoothly; feels soapy or greasy; splits into thin flakes | 1 |
| | B. | Cannot be scratched by a fingernail but can be scratched by a copper penny |
| | | [Amphibole asbestos] | White | Made up of slender, flexible fibers that can be pulled apart | 1-2½ |
| | | [Anhydrite] | White | Commonly occurs as sugary-looking masses | 3-3½ |
|
| | | [Calcite] | White | Dilute hydrochloric acid fizzes on calcite; perfect cleavage in 3 directions gives rhomb-shaped fragments | 3 |
| | | [Celestite] | White | Crystals commonly prism-shaped or flat-looking; some cleavage fragments are flat and slab-like | 3-3½ |
| | | [Halite] | White | Salty taste; dissolves in water; cube-shaped cleavage fragments | 2½ |
| | | [Sulfur] | White or pale yellow | Will burn with a blue flame; commonly found as crystals, crusts, or grains | 1½-2½ |
| | C. | Cannot be scratched by a copper penny but can be scratched by an ordinary pocket knife |
| | | [Anhydrite] | White | Commonly occurs as sugary-looking masses | 3-3½ |
| | | [Celestite] | White | Crystals commonly prism-shaped or flat-looking; some cleavage fragments are flat and slab-like | 3-3½ |
| | | [Dolomite] | White | Commonly occurs as granular masses and as rhomb-shaped crystals; dilute hydrochloric acid may fizz slightly on dolomite | 3½-4 |
| | | [Opal] | White | Curved, conchoidal fracture; may appear glassy, greasy, resinous, or dull | 5-6 |
| | D. | Cannot be scratched by an ordinary pocket knife but can be scratched by quartz |
| | | [Feldspar] | White | Glassy or pearly luster; good cleavage in 2 directions that meet at an angle of 90° or near 90°; common in granite and pegmatite rocks | 6 |
| | | [Opal] | White | Curved, conchoidal fracture; may appear glassy, greasy, resinous, or dull | 5-6 |
| | | [Quartz] | White | Curved conchoidal fracture; occurs as chert and chalcedony | 7 |
| 8. | NONMETALLIC luster, YELLOW color |
|---|
| | A. | Can be scratched by a fingernail |
| | | [Carnotite] | Yellow | Bright canary yellow or lemon yellow; radioactive; occurs as crusts and powdery masses | 2 |
| | | [Gypsum] | White | Yellowish; soft; occurs as crystals or as fibrous, granular, compact or earthy masses | 2 |
| | | [Limonite] | Rusty yellowish brown | Brownish-yellow color; may be soft and earthy | 1+ |
|
| | | [Muscovite] (white [mica]) | White | Light colored; splits into thin, flat, [transparent] sheets that will bend without breaking | 2-2½ |
| | | [Sulfur] | White or pale yellow | Will burn with a blue flame; commonly found as crystals, crusts, or grains | 1½-2½ |
| | | [Uranophane] | Light yellow to light yellow orange | Yellow to yellow-orange color; radioactive | 2-3 |
| | B. | Cannot be scratched by a fingernail but can be scratched by a copper penny |
| | | [Barite] | White | Rather heavy; cleavage fragments may be flat and slab-like | 3-3½ |
| | | [Calcite] | White | Yellowish; dilute hydrochloric acid fizzes on calcite; perfect cleavage in 3 directions gives rhomb-shaped fragments | 3 |
| | | [Muscovite] (white mica) | White | Light colored; splits into thin, flat, transparent sheets that will bend without breaking | 2-2½ |
| | | [Sulfur] | White or pale yellow | Will burn with a blue flame; commonly found as crystals, crusts, or grains | 1½-2½ |
| | | [Uranophane] | Light yellow to light yellow orange | Yellow to yellow-orange color; radioactive | 2-3 |
| | C. | Cannot be scratched by a copper penny but can be scratched by an ordinary pocket knife |
| | | [Barite] | White | Rather heavy; cleavage fragments may be flat and slab-like | 3-3½ |
| | | [Opal] | White | Curved, conchoidal fracture; may appear glassy, greasy, resinous, or dull | 5-6 |
| | D. | Cannot be scratched by an ordinary pocket knife but can be scratched by quartz |
| | | [Feldspar] | White | Glassy or pearly luster; good cleavage in 2 directions that meet at an angle of 90° or near 90° | 6 |
| | | [Garnet] | White | Commonly occurs as crystals | 6½-7 |
| | | [Opal] | White | Curved, conchoidal fracture; may appear glassy, greasy, resinous, or dull | 5-6 |
| | | [Quartz] | White | Curved conchoidal fracture; brownish-yellow smoky quartz crystals commonly 6-sided prisms with pyramid-like ends; chalcedony and [jasper] may be a shade of yellow, too | 7 |
|
| 9. | NONMETALLIC luster, BROWN color |
|---|
| | A. | Can be scratched by a fingernail |
| | | [Gypsum] | White | Brownish; soft; occurs as crystals or as fibrous, granular, compact or earthy masses | 2 |
| | | [Limonite] | Rusty yellowish brown | May be soft and earthy | 1+ |
| | | [Muscovite] (white mica) | White | Light colored; splits into thin, flat, transparent sheets that will bend without breaking | 2-2½ |
| | | [Sulfur] | White or pale yellow | Will burn with a blue flame; commonly found as crystals, crusts, or grains | 1½-2½ |
| | B. | Cannot be scratched by a fingernail but can be scratched by a copper penny |
| | | [Barite] | White | Rather heavy; cleavage fragments may be flat and slab-like | 3-3½ |
| | | [Biotite] (black mica) | White | Dark brown; splits into thin, flat sheets that will bend without breaking | 2½-3 |
| | | [Calcite] | White | Dilute hydrochloric acid fizzes on calcite; perfect cleavage in 3 directions gives rhomb-shaped fragments | 3 |
| | | [Halite] | White | Salty taste; dissolves in water; cube-shaped cleavage fragments | 2½ |
| | | [Muscovite] (white mica) | White | Light colored; splits into thin, flat, transparent sheets that will bend without breaking | 2-2½ |
| | | [Sulfur] | White or pale yellow | Will burn with a blue flame; commonly found as crystals, crusts, or grains | 1½-2½ |
| | C. | Cannot be scratched by a copper penny but can be scratched by an ordinary pocket knife |
| | | [Barite] | White | Rather heavy; cleavage fragments may be flat and slab-like | 3-3½ |
| | | [Dolomite] | White | Commonly occurs as granular masses and as rhomb-shaped crystals; dilute hydrochloric acid may fizz slightly on dolomite | 3½-4 |
| | | [Fluorite] | White | Cleavage in 4 directions can give fragments that are shaped like octahedrons; crystals commonly cube-shaped | 4 |
| | D. | Cannot be scratched by an ordinary pocket knife but can be scratched by quartz |
| | | [Cassiterite] | Pale brown, pale yellow, or white | Brown, reddish brown, or yellowish brown; heavy; dull to brilliant luster | 6-7 |
|
| | | [Feldspar] | White | Glassy or pearly luster; good cleavage in 2 directions that meet at an angle of 90° or near 90°; common in granite and pegmatite rocks | 6 |
| | | [Garnet] | White | Commonly occurs as crystals | 6½-7 |
| | | [Quartz] | White | Curved conchoidal fracture; brown smoky quartz crystals commonly 6-sided prisms with pyramid-like ends; chalcedony, chert, and jasper may be a shade brown, too | 7 |
| | | [Tourmaline] | White | Dark brown variety is [dravite]; notice hardness, striations on crystals, and triangular cross section of some crystals | 7-7½ |
| | E. | Cannot be scratched by quartz |
| | | [Tourmaline] | White | Dark brown variety is dravite; notice hardness, striations on crystals, and triangular cross section of some crystals | 7-7½ |
| 10. | NONMETALLIC luster, BLACK color |
|---|
| | A. | Cannot be scratched by a fingernail but can be scratched by a copper penny |
| | | [Biotite] (black mica) | White | Splits into thin, flat sheets that will bend without breaking | 2½-3 |
| | B. | Cannot be scratched by an ordinary pocket knife but can be scratched by quartz |
| | | [Garnet] | White | Commonly occurs as crystals | 6½-7 |
| | | [Quartz] | White | Curved conchoidal fracture; brownish-black [smoky quartz] crystals commonly 6-sided prisms with pyramid-like ends; chalcedony and chert may be black, too | 7 |
| | | [Tourmaline] | White | Black variety is [schorl]; notice hardness, striations on crystals, and triangular cross section of some crystals | 7-7½ |
| | C. | Cannot be scratched by quartz |
| | | [Tourmaline] | White | Black variety is schorl; notice hardness, striations on crystals, and triangular cross section of some crystals | 7-7½ |
| 11. | NONMETALLIC luster, GREEN color |
|---|
| | A. | Can be scratched by a fingernail |
| | | [Amphibole asbestos] | White | Made up of slender, flexible fibers that can be pulled apart | 1-2½ |
|
| | | [Cerargyrite] | Shiny white or gray | Light greenish color; appears waxy; knife cuts it smoothly; turns violet brown to black when exposed to light | 1-1½ |
| | | [Muscovite] (white mica) | White | Light colored; splits into thin, flat, transparent sheets that will bend without breaking | 2-2½ |
| | | [Sulfur] | White or pale yellow | Greenish; will burn with a blue flame; commonly found as crystals, crusts, or grains | 1½-2½ |
| | | [Talc] | White | Light greenish color; knife cuts it smoothly; feels soapy or greasy; splits into thin flakes | 1 |
| | B. | Cannot be scratched by a fingernail but can be scratched by a copper penny |
| | | [Amphibole asbestos] | White | Made up of slender, flexible fibers that can be pulled apart | 1-2½ |
| | | [Biotite] (black mica) | White | Dark green; splits into thin, flat, [translucent] sheets that will bend without breaking | 2½-3 |
| | | [Calcite] | White | Dilute hydrochloric acid fizzes on calcite; perfect cleavage in 3 directions gives rhomb-shaped fragments | 3 |
| | | [Halite] | White | Greenish tint; salty taste; dissolves in water; cube-shaped cleavage fragments | 2½ |
| | | [Muscovite] (white mica) | White | Light colored; splits into thin, flat, transparent sheets that will bend without breaking | 2-2½ |
| | | [Serpentine] | White | Two kinds: silky and fibrous, waxy and platy | 2½-4 |
| | | [Sulfur] | White or pale yellow | Greenish; will burn with a blue flame; commonly found as crystals, crusts, or grains | 1½-2½ |
| | C. | Cannot be scratched by a copper penny but can be scratched by an ordinary pocket knife |
| | | [Fluorite] | White | Cleavage in 4 directions can give fragments shaped like octahedrons; crystals commonly cubes | 4 |
| | | [Malachite] | Green | Bright green color; dilute hydrochloric acid will fizz on [malachite] | 3½-4 |
| | | [Serpentine] | White | Two kinds: silky and fibrous, waxy and platy | 2½-4 |
| | D. | Cannot be scratched by an ordinary pocket knife but can be scratched by quartz |
| | | [Feldspar] | White | Glassy or pearly luster; good cleavage in 2 directions that meet at an angle of 90° or near 90° | 6 |
| | | [Garnet] | White | Commonly occurs as crystals | 6½-7 |
|
| 12. | NONMETALLIC luster, BLUE color |
|---|
| | A. | Cannot be scratched by a fingernail but can be scratched by a copper penny |
| | | [Anhydrite] | White | Commonly occurs as sugary-looking masses | 3-3½ |
| | | [Barite] | White | Rather heavy; cleavage fragments may be flat and slab-like | 3-3½ |
| | | [Calcite] | White | Dilute hydrochloric acid fizzes on calcite; perfect cleavage in 3 directions gives rhomb-shaped fragments | 3 |
| | | [Celestite] | White | Not quite as heavy as barite; crystals commonly prism-shaped or flat-looking; some cleavage fragments are flat and slab-like | 3-3½ |
| | | [Halite] | White | Salty taste; dissolves in water; cube-shaped cleavage fragments | 2½ |
| | B. | Cannot be scratched by a copper penny but can be scratched by an ordinary pocket knife |
| | | [Anhydrite] | White | Commonly occurs as sugary-looking masses | 3-3½ |
| | | [Azurite] | Blue | Bright, intense blue color; dilute hydrochloric acid will fizz on [azurite] | 3½-4 |
| | | [Barite] | White | Rather heavy; cleavage fragments may be flat and slab-like | 3-3½ |
| | | [Celestite] | White | Not quite as heavy as barite; crystals commonly prism-shaped or flat-looking; some cleavage fragments are flat and slab-like | 3-3½ |
| | | [Fluorite] | White | Cleavage in 4 directions can give fragments that are shaped like octahedrons; crystals commonly cube-shaped | 4 |
| | | [Opal] | White | Curved, conchoidal fracture; may appear glassy, greasy, resinous, or dull; milky white and bluish-white precious opal shows plays of colors | 5-6 |
| | C. | Cannot be scratched by an ordinary pocket knife but can be scratched by quartz |
| | | [Feldspar] | White | Glassy or pearly luster; good cleavage in 2 directions that meet at an angle of 90° or near 90° | 6 |
| | | [Opal] | White | Curved, conchoidal fracture; may appear glassy, greasy, resinous, or dull; milky white and bluish-white precious opal shows plays of colors | 5-6 |
|
| | | [Quartz] | White | Curved conchoidal fracture; occurs as [crystalline] quartz and as bluish chalcedony | 7 |
| | D. | Cannot be scratched by quartz |
| | | [Topaz] | White | Perfect basal cleavage gives flat, plate-like fragments; notice hardness | 8 |
| 13. | NONMETALLIC luster, RED or PINK color |
|---|
| | A. | Can be scratched by a fingernail |
| | | [Gypsum] | White | Reddish; soft; occurs as crystals or as fibrous, granular, compact, or earthy masses | 2 |
| | | [Hematite] | Dark reddish brown | Brownish-red color; soft and earthy | 1+ |
| | | [Sulfur] | White or pale yellow | Reddish; will burn with blue flame; commonly found as crystals, crusts, or grains | 1½-2½ |
| | B. | Cannot be scratched by a fingernail but can be scratched by a copper penny |
| | | [Anhydrite] | White | Pinkish tint; commonly occurs as sugary-looking masses | 3-3½ |
| | | [Barite] | White | Pinkish tint; rather heavy; cleavage fragments may be flat and slab-like | 3-3½ |
| | | [Calcite] | White | Pink color; dilute hydrochloric acid fizzes on calcite; perfect cleavage in 3 directions gives rhomb-shaped fragments | 3 |
| | | [Cinnabar] | Dark red | Dark red or bright yellowish-red color; shiny, brilliant luster when pure; dull and earthy when impure; heavy | 2½ |
| | | [Halite] | White | Reddish tint; salty taste; dissolves in water; cube-shaped cleavage fragments | 2½ |
| | | [Sulfur] | White or pale yellow | Reddish; will burn with blue flame; commonly found as crystals, crusts, or grains | 1½-2½ |
| | C. | Cannot be scratched by a copper penny but can be scratched by an ordinary pocket knife |
| | | [Anhydrite] | White | Pinkish tint; commonly occurs as sugary-looking masses | 3-3½ |
| | | [Barite] | White | Pinkish tint; rather heavy; cleavage fragments may look flat and slab-like | 3-3½ |
| | | [Dolomite] | White | Pink color; commonly occurs as granular masses and as rhomb-shaped crystals; dilute hydrochloric acid may fizz slightly on dolomite | 3½-4 |
|
| | | [Fluorite] | White | Pink color; cleavage in 4 directions can give fragments that are shaped like octahedrons; crystals commonly cubes | 4 |
| | | [Opal] | White | Reddish color; curved, conchoidal fracture; may appear glassy, greasy, resinous, or dull | 5-6 |
| | D. | Cannot be scratched by an ordinary pocket knife but can be scratched by quartz |
| | | [Feldspar] | White | Glassy or pearly luster; good cleavage in 2 directions that meet at an angle of 90° or near 90° | 6 |
| | | [Garnet] | White | Commonly occurs as crystals | 6½-7 |
| | | [Opal] | White | Reddish color; curved, conchoidal fracture; may appear glassy, greasy, resinous, or dull | 5-6 |
| | | [Quartz] | White | Curved, conchoidal fracture; occurs as [rose quartz], as pink chert, and as [agate] and jasper | 7 |
| 14. | NONMETALLIC luster, PURPLE or VIOLET color |
|---|
| | A. | Cannot be scratched by a copper penny but can be scratched by an ordinary pocket knife |
| | | [Fluorite] | White | Cleavage in 4 directions can give fragments that are shaped like octahedrons; crystals commonly cubes | 4 |
| | B. | Cannot be scratched by an ordinary pocket knife but can be scratched by quartz |
| | | [Quartz], variety: [amethyst] | White | Curved, conchoidal fracture; amethyst crystals commonly 6-sided prisms with pyramid-like ends | 7 |
| 15. | NONMETALLIC luster, COLORLESS |
|---|
| | A. | Can be scratched by a fingernail |
| | | [Cerargyrite] | Shiny white or gray | Appears waxy; knife cuts it smoothly; turns violet brown to black when exposed to light | 1-1½ |
| | | [Gypsum] | White | Transparent [selenite] variety commonly occurs as flat, diamond-shaped crystals; splits into thin, flat sheets that will not bend without breaking | 2 |
| | | [Muscovite] (white mica) | White | Splits into thin, flat, transparent sheets that will bend without breaking | 2-2½ |
|
| | B. | Cannot be scratched by a fingernail but can be scratched by a copper penny |
| | | [Barite] | White | Rather heavy; cleavage fragments may be flat and slab-like | 3-3½ |
| | | [Calcite] | White | Dilute hydrochloric acid fizzes on calcite; perfect cleavage in 3 directions gives rhomb-shaped fragments | 3 |
| | | [Celestite] | White | Not quite as heavy as barite; crystals commonly prism-shaped or flat-looking; some cleavage fragments are flat and slab-like | 3-3½ |
| | | [Halite] | White | Salty taste; dissolves in water; cube-shaped cleavage fragments | 2½ |
| | | [Muscovite] (white mica) | White | Splits into thin, flat, transparent sheets that will bend without breaking | 2-2½ |
| | C. | Cannot be scratched by a copper penny but can be scratched by an ordinary pocket knife |
| | | [Barite] | White | Rather heavy; cleavage fragments may be flat and slab-like | 3-3½ |
| | | [Celestite] | White | Not quite as heavy as barite; crystals commonly prism-shaped or flat-looking; some cleavage fragments are flat and slab-like | 3-3½ |
| | | [Dolomite] | White | Commonly occurs as granular masses and as rhomb-shaped crystals; dilute hydrochloric acid may fizz slightly on dolomite | 3½-4 |
| | | [Fluorite] | White | Cleavage in 4 directions can give fragments that are shaped like octahedrons; crystals commonly cubes | 4 |
| | | [Opal] | White | Curved, conchoidal fracture; transparent [hyalite] variety resembles ice | 5-6 |
| | D. | Cannot be scratched by an ordinary pocket knife but can be scratched by quartz |
| | | [Opal] | White | Curved, conchoidal fracture; transparent hyalite variety resembles ice | 5-6 |
| | | [Quartz] | White | Curved, conchoidal fracture; [rock crystal] quartz commonly 6-sided prism with pyramid-like ends | 7 |
| | E. | Cannot be scratched by quartz |
| | | [Topaz] | White | Perfect basal cleavage gives flat, plate-like fragments; notice hardness | 8 |