MT2: Minerals with Nonmetallic Luster
- Hardness >5.5
- Streak that is white or appears white like
- No cleavage
Cleavage |
Other |
Mineral |
None |
Brown, pink, blue or gray in color; six-sided prismatic crystals; ruby (red color) and sapphire (blue) are gem varieties of this mineral |
Corundum Al2O3 |
Black, pink, blue, green, brown in color; vitreous luster; thin crystals with triangular cross sections and striated faces |
Tourmaline Complex hydrous silicate |
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Reddish brown, yellowish tan in color; vitreous to resinous luster; twelve-sided crystals; broken surfaces may resemble cleavages |
Garnet Ca-Mg-Fe-Al silicate |
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Red-brown, brownish-black in color; vitreous, resinous or dull luster; prismatic and X or cross-shaped crystals |
Staurolite Hydrous Fe-Al silicate |
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Varied appearance with larger crystalline varieties exhibiting a clear, milky, white, purple, smokey or pink color; vitreous luster; Small crystalline varieties exhibiting gray, black, brown or multicolor banded appearance; vitreous luster |
Quartz SiO2 |
|
Olive-green to yellow-green in color; vitreous to dull luster |
Olivine (Mg,Fe)SiO4 |
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Colorless, white, or pale shades of yellow, green, red or blue in color; vitreous to resinous luster |
Opal SiO2 nH2O |
