_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
[Illustration: Diamond Star of Sierra Leone.]
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