Milarite Value, Price, and Jewelry Information

MILARITE: Tsumeb, Namibia (0.53). Photo © Joel E. Arem, PhD, FGA. Used with permission.

Milarite

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 Information

Data Value
Name Milarite
Colors Colorless, pale green, yellowish, yellowish green.
Crystallography Hexagonal. Crystals prismatic and tabular; in grains.
Refractive Index 1.529-1.551
Luster Vitreous.
Hardness 5.5-6
Fracture Conchoidal to uneven
Specific Gravity 2.46-2.61
Birefringence 0.003
Cleavage None
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.
Luminescence Present No
Transparency Transparent to opaque.
Absorption Spectrum Not diagnostic.
Formula

K2Ca4Be4Al2Si24O60·H2O.

Optics

= 1.532-1.551: e = 1.529-1-548. Uniaxial (-).

Optic Sign Uniaxial -

Osumilite Group.

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.