Lapis Lazuli

Lapis lazuli is a gemstone of the kind that might have come straight out of the Arabian Nights: a deep blue with golden inclusions of pyrites which shimmer like little stars.

Color Blue, mottled with white calcite and brassy pyrite
Mohs scale hardness 5.0 - 5.5
Specific gravity 2.70 - 2.90
Refractive index 1.500 - 1.550