Aheylite
| Aheylite | ||
|---|---|---|
Specific gravity 2.84 | | |
| Optical properties | Biaxial (+) | |
| Refractive index | ~1.63 | |
| References | [2][3][4] | |
Aheylite is a rare
group in 1984 by International Mineralogical Association Commission on New Minerals and Mineral Names.Composition
The turquoise group has a basic formula of A0–1B6(PO4)4−x(PO3OH)x(OH)8·4H2O. This group contains five other minerals. In addition to aheylite:
chalcosiderite, and an unnamed Fe2+-Fe3+ analogue. Aheylite is distinguished in this group by having Fe2+ dominant in the A-site. The ideal aheylite has a formula of Fe2+Al6(PO4)4(OH)8·4H2O. Its color is pale blue or green. With turquoise family the blue color is said to come from the octahedral coordination of Cu2+ in the absence of Fe3+.[5]
Name and discovery
It was first described for an occurrence in the Huanuni mine, Huanuni, Oruro Department, Bolivia, and named for Allen V. Heyl (1918–2008), an economic geologist for the United States Geological Survey.[3] It was discovered by Eugene Foord and Joseph Taggart.[5]
Occurrence
In addition to the
It is adeposit associated with variscite, vivianite, wavellite, cassiterite, sphalerite, pyrite and quartz in the type locality.[2][4]
Physical properties
It is found as an isolated mass of hemispheres and spheres clumped together. It has a vitreous to dull luster. It has a hackly to splintery fracture and it has a brittle tenacity. The hardness is about 5–5.5, and the
specific gravity is 2.84. As far as optical properties, it had thin flakes; ipale blue, green to blue-green color; it streaks white, and has a subvitreous luster.[5]
References
- S2CID 235729616.
- ^ a b c d Aheylite. Handbook of Mineralogy
- ^ a b c Aheylite. Mindat.org
- ^ a b Aheylite. Webmineral
- ^ a b c Eugene E. Foord and Joseph E. Taggart, Jr., A reexamination of the turquoise group: the mineral aheylite, plane rite (redefined), turquoise and coeruleolactite, Mineralogical Magazine, February 1998, Vol. 62(1), pp. 93–111