# Mineral Hardness Color Transparency Crystal System Probability See More
1Cordierite7.0 - 7.5Grey, blue, blue-violet, greenish, yellowish brown, colourless to very light blue in transmitted light.Transparent, TranslucentOrthorhombic0.048
2Andalusite6.5 - 7.5Pink to red brown, occasionally yellow, green, white, gray rarely violetTransparent, TranslucentOrthorhombic0.009
3Schorl7.0Bluish-black to black, sometimes brownish-black, rarely greenish-black.Translucent, OpaqueTrigonal0.007
4Cassiterite6.0 - 7.0Black, yellow, brown, red or white.Transparent, Translucent, OpaqueTetragonal0.005
5Sillimanite6.5 - 7.5Colorless, white, yellow, brown, green, gray.Transparent, TranslucentOrthorhombic0.004
6Narsarsukite7.0Yellow, yellowish-white, grayish-white, honey-yellow, tan, greenish-yellowTransparent, TranslucentTetragonal0.003
7Almandine7.0 - 7.5Deep red, brownish red, red-violet, blackTransparent, TranslucentIsometric0.003
8Dravite7.0Pale brown to dark-brown to brownish-black, also dark-yellow, blue.Transparent, TranslucentTrigonal0.003
9Ussingite6.0 - 7.0Pale to medium violet, reddish violet, sometimes barely tinted purpleTransparent, TranslucentTriclinic0.003
10Dumortierite7.0 - 8.0Blue, greenish-blue, violet-blue, pale blue, pink, redTranslucentOrthorhombic0.003
11Forsterite7.0Green, pale yellow or white.Transparent, TranslucentOrthorhombic0.002
12Thorianite6.5 - 7.0Dark grey, brown-blackIsometric0.002