Rocks and Minerals

Color Index and Texture

Color Index

Felsic (high silica, light-colored; 0–15% dark minerals)

Texture

Phaneritic (coarse-grained; intrusive, large crystals)

Granite

Name, Color Index, Texture

Color Index: Mafic (low silica, dark-colored; 45–85% dark minerals) Texture:

Phaneritic (coarse-grained; intrusive)

Gabbro

Name, Color Index, Texture

Diorite

Color Index: Intermediate (15–45% dark minerals; salt-and-pepper appearance)

Texture: Phaneritic (coarse-grained; intrusive)

Name, Color Index, Texture

Color Index: Felsic (light-colored; high silica)

Texture: Aphanitic (fine-grained; extrusive, small crystals)

Rhyolite

Name, Color Index, Texture

Color Index: Intermediate (medium-gray; 15–45% dark minerals)

Texture: Aphanitic/Porphyritic (fine-grained; extrusive, may show porphyritic texture)

Andesite

Name, Color Index, Texture

Color Index: Felsic to Intermediate (light to gray, alkali feldspar-rich)

Texture: Aphanitic (fine-grained; extrusive, may show porphyritic texture)

Trachyte

Name, color index, texture

Color Index: Mafic (dark-colored; >45% dark minerals, rich in Fe & Mg)

Texture: Aphanitic (fine-grained; extrusive, rapid cooling)

Basalt

Color: _____________

Luster: _____________

Streak: _____________

Hardness (Fingernail): _____________

Hardness (Coin): _____________

Hardness (Nails): _____________

Diaphaneity: _____________

Pyrite

COLOR: pale brass-yellow

LUSTER: metallic

STREAK: greenish-black or brownish-black

HARDNESS: 6 to 6.5

              FINGERNAILS: Harder than fingernails (2.5)

              COINS: Harder than copper coins (3-4)

              NAILS: Harder than iron nails (4-4.5)

DIAPHANEITY:  opaque

Color: _____________

Luster: _____________

Streak: _____________

Hardness (Fingernail): _____________

Hardness (Coin): _____________

Hardness (Nails): _____________

Diaphaneity: _____________

ROSE QUARTZ

COLOR: pink

LUSTER: non-metallic - vitreous

STREAK: white

HARDNESS: 7

              FINGERNAILS: harder than a fingernail (2.5)

              COINS: harder than a copper coin (3-4)

              NAILS: Harder than an iron nail (4-4.5)

DIAPHANEITY: translucent

Color: _____________

Luster: _____________

Streak: _____________

Hardness (Fingernail): _____________

Hardness (Coin): _____________

Hardness (Nails): _____________

Diaphaneity: _____________

PINK TOURMALINE

COLOR: pink / rubellite

LUSTER: vitreous

STREAK: white

HARDNESS: 7 to 7.5

              FINGERNAILS: harder than a fingernail (2.5)

              COINS: Harder than a copper coin (3-4)

              NAILS: Harder than an iron nail (4-4.5)

DIAPHANEITY: translucent / transparent to opaque

Color: _____________

Luster: _____________

Streak: _____________

Hardness (Fingernail): _____________

Hardness (Coin): _____________

Hardness (Nails): _____________

Diaphaneity: _____________

OPAL

COLOR: colorless, white / opalescence

LUSTER: vitreous (glassy) to waxy or resinous

STREAK: white

HARDNESS: 5.5 to 6.5

              FINGERNAILS: harder than a fingernail (2.5)

              COINS: Harder than a copper coin (3-4)

NAILS: Harder than an iron nail (4-4.5)

DIAPHANEITY: transparent to translucent to opaque

Color: _____________

Luster: _____________

Streak: _____________

Hardness (Fingernail): _____________

Hardness (Coin): _____________

Hardness (Nails): _____________

Diaphaneity: _____________

Garnet

• Color: Usually deep red to reddish-brown (can also be green, yellow, or black depending on variety)

• Luster: Vitreous (glassy)

• Streak: Colorless (no streak; harder than streak plate)

• HARDNESS: 5.5 to 6.5

                FINGERNAILS: harder than a fingernail (2.5)

                COINS: Harder than a copper coin (3-4)

  NAILS: Harder than an iron nail (4-4.5)

  DIAPHANEITY: transparent to translucent to opaque

Color: _____________

Luster: _____________

Streak: _____________

Hardness (Fingernail): _____________

Hardness (Coin): _____________

Hardness (Nails): _____________

Diaphaneity: _____________

AVENTURINE QUARTZ

COLOR: green

LUSTER: vitreous

STREAK: white

HARDNESS: 6.5 to 7

              FINGERNAILS: harder than a fingernail (2.5)

              COINS: Harder than a copper coin (3-4)

              NAILS: Harder than an iron nail (4-4.5)

DIAPHANEITY: translucent / opaque

Color: _____________

Luster: _____________

Streak: _____________

Hardness (Fingernail): _____________

Hardness (Coin): _____________

Hardness (Nails): _____________

Diaphaneity: _____________

EPIDOTE

COLOR: pistachio-green or yellowish-green / brownish-green or even black

LUSTER: vitreous / resinous

STREAK: grayish-white or white

HARDNESS: 6 to 7

              FINGERNAILS: harder than a fingernail (2.5)

              COINS: Harder than a copper coin (3-4)

              NAILS: Harder than an iron nail (4-4.5)

DIAPHANEITY:  transparent to translucent to nearly opaque

Color: _____________

Luster: _____________

Streak: _____________

Hardness (Fingernail): _____________

Hardness (Coin): _____________

Hardness (Nails): _____________

Diaphaneity: _____________

SODALITE

COLOR: royal blue to violet-blue

LUSTER:  vitreous (glassy) to greasy or dull luster

STREAK: white or grayish-white

HARDNESS:  5.5 to 6

              FINGERNAILS: harder than a fingernail (2.5)

              COINS: Harder than a copper coin (3-4)

              NAILS: Harder than an iron nail (4-4.5)

DIAPHANEITY: translucent

Color: _____________

Luster: _____________

Streak: _____________

Hardness (Fingernail): _____________

Hardness (Coin): _____________

Hardness (Nails): _____________

Diaphaneity: _____________

SETONITE / AFRICAN BLOODSTONE

COLOR: red and dark green

LUSTER: vitreous

STREAK: white

HARDNESS: 6.5 to 7

              FINGERNAILS: harder than a fingernail (2.5)

              COINS: Harder than a copper coin (3-4)

              NAILS: Harder than an iron nail (4-4.5)

DIAPHANEITY:  translucent

Color: _____________

Luster: _____________

Streak: _____________

Hardness (Fingernail): _____________

Hardness (Coin): _____________

Hardness (Nails): _____________

Diaphaneity: _____________

AMETHYST

COLOR: purple

LUSTER: vitreous

STREAK: white

HARDNESS: 7

              FINGERNAILS: harder than a fingernail (2.5)

              COINS: Harder than a copper coin (3-4)

              NAILS: Harder than an iron nail (4-4.5)

DIAPHANEITY: transparent to translucent

Color: _____________

Luster: _____________

Streak: _____________

Hardness (Fingernail): _____________

Hardness (Coin): _____________

Hardness (Nails): _____________

Diaphaneity: _____________

MALACHITE

COLOR: green

LUSTER: Vitreous (glassy) to adamantine/ Silky/ Dull to earthy

STREAK: pale green or light green

HARDNESS: 3.5 to 4

              FINGERNAILS: harder than a fingernail (2.5)

              COINS:  softer than copper coin (hardness of 3-4)

              NAILS: softer than an iron nail (hardness 4-4.5)

DIAPHANEITY: opaque to translucent

Color: _____________

Luster: _____________

Streak: _____________

Hardness (Fingernail): _____________

Hardness (Coin): _____________

Hardness (Nails): _____________

Diaphaneity: _____________

RED JASPER

COLOR: brick red to a deep brownish-red

LUSTER: dull or waxy

STREAK: white

HARDNESS: 6.5 to 7

              FINGERNAILS: harder than a fingernail (2.5)

              COINS: Harder than a copper coin (3-4)

              NAILS: Harder than an iron nail (4-4.5)

DIAPHANEITY:  opaque

Color: _____________

Luster: _____________

Streak: _____________

Hardness (Fingernail): _____________

Hardness (Coin): _____________

Hardness (Nails): _____________

Diaphaneity: _____________

RAINBOW/ GREEN FLUORITE

COLOR: Green Fluorite: emerald green/ Rainbow Fluorite: purple, green, and blue,

LUSTER: vitreous

STREAK: white

HARDNESS: 4

              FINGERNAILS: harder than a fingernail (2.5)

              COINS: harder than a copper coin (3-4)

              NAILS:  softer than iron nail (4-4.5)

DIAPHANEITY:  transparent to translucent

Color: _____________

Luster: _____________

Streak: _____________

Hardness (Fingernail): _____________

Hardness (Coin): _____________

Hardness (Nails): _____________

Diaphaneity: _____________

TIGER’S EYE

COLOR: golden to red-brown

LUSTER: silky

STREAK: white

HARDNESS: 6.5 to 7

              FINGERNAILS: harder than a fingernail (2.5)

              COINS: Harder than a copper coin (3-4)

              NAILS: Harder than an iron nail (4-4.5)

DIAPHANEITY: translucent to opaque

Color: _____________

Luster: _____________

Streak: _____________

Hardness (Fingernail): _____________

Hardness (Coin): _____________

Hardness (Nails): _____________

Diaphaneity: _____________

APATITE

COLOR: green

LUSTER: vitreous/  sub-resinous or dull

STREAK: white

HARDNESS: 5

              FINGERNAILS: harder than a fingernail (2.5)

              COINS: Harder than a copper coin (3-4)

              NAILS: softer than iron nail (4-4.5)

DIAPHANEITY:  transparent to translucent

Color: _____________

Luster: _____________

Streak: _____________

Hardness (Fingernail): _____________

Hardness (Coin): _____________

Hardness (Nails): _____________

Diaphaneity: _____________

AMAZONITE

COLOR: blue-green, greenish-blue, or turquoise

LUSTER: vitreous

STREAK: white

HARDNESS: 6 to 6.5

              FINGERNAILS: harder than a fingernail (2.5)

              COINS:  Harder than a copper coin (3-4)

              NAILS: Harder than an iron nail (4-4.5)

DIAPHANEITY:  translucent to opaque

Color: _____________

Luster: _____________

Streak: _____________

Hardness (Fingernail): _____________

Hardness (Coin): _____________

Hardness (Nails): _____________

Diaphaneity: _____________

LAPIS LAZULI

COLOR: deep blue

LUSTER: dull/ vitreous (glassy) or waxy

STREAK: light blue to blue

HARDNESS: 5 to 6

              FINGERNAILS: harder than a fingernail (2.5)

              COINS: harder than a copper coin (3-4)

              NAILS: harder than an iron nail (4-4.5)

DIAPHANEITY:  opaque to translucent

Color: _____________

Luster: _____________

Streak: _____________

Hardness (Fingernail): _____________

Hardness (Coin): _____________

Hardness (Nails): _____________

Diaphaneity: _____________

OBSIDIAN

COLOR: jet-black

LUSTER: vitreous

STREAK: white

HARDNESS: 5 to 6

              FINGERNAILS: harder than a fingernail (2.5)

              COINS: Harder than a copper coin (3-4)

              NAILS: Harder than an iron nail (4-4.5)

DIAPHANEITY:  translucent to opaque