Alkali Feldspar Group—

Orthoclase: Pale yellow, flesh red

Amazonite: Yellow green to greenish blue

Moonstone: Colorless; also white to yellowish, and reddish to bluish gray

Garnet (hardness: 6.5-7.5 Mohs)

A group of silicate minerals

Specific gravity: 3.5-4.3

Almandine: Orangy red to purplish red

Almandine-spessartine: Reddish orange

Andradite: Yellowish green to orangy yellow to black

Demantoid: Green to yellow green andradite

Topazolite: Yellow to orangy yellow

Grossular: Colorless; also orange, pink, yellow, and brown

Tsavorite: Green to yellowish green

Hessonite: Yellow orange to red

Pyrope: Colorless; also pink to red

Chrome pyrope: Orange red

Pyrope-Almadine: Reddish orange to red purple

Pyrope-Spessartine: Greenish yellow to purple

Malaia: Yellowish to reddish orange to brown

Color-change garnet: Blue green in daylight to purple red in incandescent light

Rhodolite: Purplish red to red purple

Spessartine: Yellowish orange

Uvarovite: Emerald green

Jade (hardness: 6 Mohs)

Nephrite

Calcium magnesium silicate

Specific gravity: 2.9-3.1

White, deep green, creamy brown

Jadeite

Sodium aluminum silicate

Specific gravity: 3.1-3.5

White, leafy and blue green, emerald green, lavender, dark blue green and greenish black, deep emerald-green

Lapis lazuli (hardness: 5-5.5 Mohs)

A rock composed mainly of the mineral lazurite with variable amounts of pyrite (brassy flecks) and white calcite

Specific gravity: 2.7-2.9

Deep blue, azure blue, greenish blue (bluish color with flecks of white and gold)

Opal (hardness: 5.5-6.5 Mohs)

Hydrated silica

Specific gravity: 1.98-2.25

White opal: Opaque, porcelain-like white material; colors resemble flashes or speckles

Black opal: Flashes and speckles appear against black background

Water opal: A transparent, colorless opal is the background for brilliant flashes of color

Fire opal: Reddish or orange opal

Peridot [Olivine] (hardness: 7 Mohs)

Magnesium iron silicate

Specific gravity: 3.22-3.45

Olive to lime green

Quartz (hardness: 7 Mohs)

Silicon dioxide or silica

Specific gravity: 2.65

Coarsely crystalline varieties of silica—

Rock crystal: Colorless