MT3: Minerals with Nonmetallic Luster
- Hardness >5.5
- Streak that is white or appears white like
Cleavage |
Other |
Mineral |
One |
Colorless, yellow, brown, pink, blue in color; vitreous luster; elongated crystals with striated faces and pointed ends |
Topaz Al2SiO4(OH,F)2 |
Bluish green, yellow, white, pink in color; elongated, six-sided crystal prisms with flat ends |
Beryl Be3Al2(Si6O18) |
|
Light blue to greenish blue in color; vitreous luster; blade-shaped crystals |
Kyanite Al2SiO5 |
|
White, pale green, brown in color; long slender crystals often in groups of parallel crystals |
Sillimanite Al2SiO5 |
|
Two |
Salmon-pink, white, gray, green in color; vitreous luster; nearly right-angle or 90 degree cleavage |
Potassium Feldspar KAlSi3O8 |
White, dark gray or sometimes buff in color; vitreous luster; nearly right-angle or 90 degree cleavage; straight or parallel striations may show |
Plagioclase Feldspar NaAlSi3O8 to CaAl2Si2O8 |
|
Pistachio green, yellowish green in color; elongated crystals or finely crystalline masses |
Epidote Hydrous Ca-Fe-Al silicate |
|
Black; vitreous luster; possible faint green-gray streak; two perfect cleavages at 124 degrees and 56 degrees; stepped cleavage faces |
Hornblend Hydrous Na-Ca-Mg-Fe-Al silicate |
|
Black, dark green in color; vitreous to dull in luster; two imperfect cleavages meeting at nearly 90 degrees (see also table MT6) |
Augite Ca-Mg-Fe silicate |