| Hornblende | |
|---|---|
-Hornblende-38354.jpg) Hornblende crystal (dark green) about 35 mm long, with apatite (white) | |
| General | |
| Category | Silicate mineral |
| Formula (repeating unit) | Ca2(Mg,Fe,Al)5(Al,Si)8O22(OH)2 |
| IMA symbol | Hbl[1] |
| Crystal system | Monoclinic |
| Space group | C2/m |
| Identification | |
| Color | Black to dark green or brown |
| Crystal habit | Hexagonal/granular |
| Cleavage | Imperfect at 56° and 124° |
| Fracture | Uneven |
| Mohs scale hardness | 5–6 |
| Luster | Vitreous to dull |
| Streak | Pale gray, gray-white,[2][3] white, colorless[4] |
| Specific gravity | 2.9 |
| Pleochroism | Strong |
| References | [5] |
Hornblende is a complex inosilicate series of minerals.[6] It is not a recognized mineral in its own right, but the name is used as a general or field term, to refer to a dark amphibole. Hornblende minerals are common in igneous and metamorphic rocks.
The general formula is (Ca,Na)2−3(Mg,Fe,Al)5(Al,Si)8O22(OH,F)2.
- ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
- ^ Ferrohornblende, Mindat.org
- ^ Magnesiohornblende, Mindat.org
- ^ "Hornblende Mineral | Uses and Properties".
- ^ Phillips, M.W.; Draheim, J.E.; Popp, R.K.; Clowe, C.A.; Pinkerton, A.A. (1989). "Effects of oxidation-dehydrogenation in tschermakitic hornblende". American Mineralogist. 74: 764–773. Retrieved 30 December 2020.
- ^ Hornblende Root Name Group, Mindat.org