MILARITE: Tsumeb, Namibia (0.53)
Milarite was originally known as a green mineral, until fine yellow crystals were discovered in Mexico in 1968. Larger Mexican crystals have transparent areas and have been faceted into small gems of pleasant appearance but great rarity.
Milarite Value
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Milarite Information
| Data | Value |
| Name | Milarite |
| Crystallography | Hexagonal. Crystals prismatic and tabular; in grains. |
| Colors | Colorless, pale green, yellowish, yellowish green. |
| Luster | Vitreous. |
| Hardness | 5.5-6. |
| Density | 2.46- 2.61. |
| Birefringence | 0.003. |
| Cleavage | None. Fracture conchoidal to uneven. Brittle. |
| Stone Sizes | Crystals occur up to about 4 cm across, but facetable areas in such crystals are very small. Stones over 1 carat could be considered large for the species. |
| Luminescence | None. |
| Spectral | Not diagnostic. |
| Formula | K2Ca4Be4Al2Si24O60·H2O. |
Osumilite Group.
Optics: o=1.532-1.551: e = 1-529-1-548
Uniaxial (—).
Occurrence: In vugs in granites and syenites: hydrothermal veins.
St. Gotthard, Switzerland: green crystals.
Guanajuato, Mexico: yellow and yellow green crystals on matrix, flat, platelike.
Africa: occasional small facetable crystals found.
Comments: Milarite was originally known as a green mineral, until fine yellow crystals were discovered in Mexico in 1968. Larger Mexican crystals have transparent areas and have been faceted into small gems of pleasant appearance but great rarity.
Name: After the Val Milar, Switzerland, because the mineral was (mistakenly) thought to have occurred there.
