Homilite
Borosilicate mineral
From Wikipedia, the free encyclopedia
Homilite is a borosilicate mineral belonging to the gadolinite group of minerals with formula Ca2(Fe,Mg)B2Si2O10.
| Homilite | |
|---|---|
| General | |
| Category | Nesosilicate |
| Formula | Ca2(Fe2+,Mg)B2Si2O10 |
| IMA symbol | Hom[1] |
| Strunz classification | 8/B.29-30 |
| Crystal system | Monoclinic |
| Crystal class | Prismatic (2/m) |
| Space group | P21/b |
| Unit cell | a = 9.78 Å, b = 7.61 Å, c = 4.78 Å; β = 90.56°; Z = ? |
| Identification | |
| Color | Greenish to brownish black |
| Mohs scale hardness | 5–5+1⁄2 |
| Luster | Vitreous, resinous |
| Diaphaneity | Opaque |
| Specific gravity | 3.34 |
| Optical properties | Biaxial (+) |
| Refractive index | nα = 1.715 nβ = 1.725 nγ = 1.738 |
| Birefringence | δ = |
| 2V angle | Measured: 80° |
| References | [2][3][4] |
It occurs as brown monoclinic crystals (space group P21/a[5]) within feldspar masses in pegmatite and was discovered in 1876 in Stoko island, Langesundfiord, Norway. The name is from the Greek for to occur together, in allusion to its association with meliphanite and allanite.
