Colorless, triangle-cut augelite, 0.41-ct, 6.3 x 5.3 mm, Champion Mine, Mono Co., California. © The Gem Trader. Used with permission.
Soft and brittle, rare augelites are difficult to cut and unsuitable for wear. Faceted transparent pieces are only found in very complete gem and mineral collections.
| Data | Value |
|---|---|
| Name | Augelite |
| Crystallography | Monoclinic. Crystals tabular and thick; prismatic; acicular. Also massive. |
| Refractive Index | 1.570-1.590 |
| Colors | Colorless, white, yellowish, pale blue, pale rose, pink, green. |
| Luster | Vitreous. Pearly on cleavage surfaces. |
| Hardness | 4.5-5 |
| Fracture | Uneven |
| Specific Gravity | 2.696-2.75 |
| Birefringence | 0.014-0.020 |
| Cleavage | Perfect 1 direction, good 1 direction |
| Dispersion | None. |
| Luminescence | Usually none, but green Peruvian material has shown light yellow fluorescence in SW, inert in LW. |
| Luminescence Present | Yes |
| Luminescence Type | Fluorescent, UV-Short |
| Transparency | Transparent. |
| Absorption Spectrum | Not diagnostic. |
| Formula | Al2PO4(OH)3 |
| Pleochroism | None. |
| Optics | α = 1.574; β = 1.576; γ = 1.588. White Mountain, California, material: α = 1.570; β = 1.574; γ = 1.590. Biaxial (+), 2V ~ 50°. |
| Optic Sign | Biaxial + |
| Etymology | From the Greek word auge for “luster,” due to the mineral’s glassy appearance. |
| Occurrence | Granitic pegmatites and hydrothermal veins. |
Augelite: California (~ 1.5, rough ½ inch across). Photo © Joel E. Arem, PhD, FGA. Used with permission.
Although new gem-quality finds of this phosphate mineral have appeared, augelites remain quite rare. Furthermore, facetable crystals are typically very small and very rarely transparent. With a hardness of 4.5-5, a brittle tenacity, and two planes of perfect and good cleavage, this gem poses some challenges to gem cutters and jewelry enthusiasts alike. Although it can occur in lovely pale greens, yellows, blues, and pinks, as well as colorless, and has a striking vitreous, glass-like luster, augelite has no dispersion or “fire” to catch the eye.
This rough and cut set features a colorless, sharp augelite crystal on quartz and a colorless, round brilliant-cut augelite. 2.1 x 1.3 x 0.8 cm (crystal), 0.95-ct (gem), Champion Mine, Mono County, California, USA. © Rob Lavinsky, www.iRocks.com. Used with permission.
Gem-quality light green augelites from a new find in Peru in 2006 have shown light yellow fluorescence under shortwave ultraviolet light. Gems from other sources have shown no fluorescence.
Yellowish green, rhomboid step-cut augelite, 1.04 cts, 7.2 x 4.3 mm, Ortega Mine, Ancash Dept., Peru. © The Gem Trader. Used with permission.
Scientists have used synthetic augelites for research purposes. However, there is no known jewelry use for this lab-created material.
No known gem treatments or enhancements.
Long the only source for facetable augelites, crystals from the Champion Mine in Mono County, California could reach about one inch in size. This source is now depleted. New facetable material has come from Peru.
Yukon Territory, Canada and Bolivia produce fine-quality crystal specimens.
Other notable sources include the following:
Lustrous augelites in a vug. The largest crystal is 1.3 cm in length. Machacamarca Mine, Machacamarca, Machacamarca District (Colavi District), Cornelio Saavedra Province, Potosi Department, Bolivia. © Rob Lavinsky, www.iRocks.com. Used with permission.
Most existing faceted gems from the California material weigh less than one carat. Some weigh up to three carats. This rare mineral very rarely yields larger stones.
Clean augelites only with a soft brush, mild detergent, and warm water. Consult our gemstone jewelry cleaning guide for more recommendations.
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