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Minyulite is a rare
It was first described in 1933 for an occurrence in Western Australia and named after the Type locality (geology), type locality, Minyulo Well in Western Australia.
Minyulite is considered as a secondary phosphate since it is formed by the alteration of a primary phosphate. It occurs in association with dufrenite, apatite, fluellite, wavellite, variscite and leucophosphite.
The mineral can be found in the underlying phosphatized rock zone of ornithogenic soil. Minyulite is not found in abundance, it can be found in the seashore of the maritime Arctic. Tatur, A., and Keck, A. (1990) Phosphates in ornithogenic soils of the Maritime Antarctic.Proc. NIPR Symp. Polar Biol: 3, 133-150.
phosphate mineral
Phosphate minerals contain the tetrahedrally coordinated phosphate (PO43−) anion along sometimes with arsenate (AsO43−) and vanadate (VO43−) substitutions, and chloride (Cl−), fluoride (F−), and hydroxide (OH−) anions that also fit ...
with a chemical formula of (redefinition, IMA21-E).
It occurs as groups of radiating fine fibrous crystals within rock cracks of phosphatic ironstone
Ironstone is a sedimentary rock, either deposited directly as a ferruginous sediment or created by chemical replacement, that contains a substantial proportion of an iron ore compound from which iron (Fe) can be smelted commercially. Not to be con ...
. Minyulite belongs to the orthorhombic crystal system. This indicates that it has three axes of unequal length yet all are perpendicular to each other. Its cell constants are a=9.35, b=9.74 c=5.52.
As for its optical properties, Minyulite is an anisotropic mineral which means the velocity of light differs when traveling through it depending on the cut of its cross-section which gives it more than one refractive index.Klein, C., and Dutrow, B.(2007) The 23rd Edition of the Manual of Mineral Science, 290 p. John Wiley and Sons, Inc. Hoboken, New Jersey, U.S.A. The mineral is optically biaxial. Its birefringence value is 0.007. It has three refractive indices
In optics, the refractive index (or refraction index) of an optical medium is a dimensionless number that gives the indication of the light bending ability of that medium.
The refractive index determines how much the path of light is bent, or ...
which are nα=1.531 nβ=1.534 nγ=1.538. Refractive indices are a ratio of the speed of light in a median with respect to the speed of light passing through the mineral.
Occurrence
It was first described in 1933 for an occurrence in Western Australia and named after the Type locality (geology), type locality, Minyulo Well in Western Australia.
Minyulite is considered as a secondary phosphate since it is formed by the alteration of a primary phosphate. It occurs in association with dufrenite, apatite, fluellite, wavellite, variscite and leucophosphite.
The mineral can be found in the underlying phosphatized rock zone of ornithogenic soil. Minyulite is not found in abundance, it can be found in the seashore of the maritime Arctic. Tatur, A., and Keck, A. (1990) Phosphates in ornithogenic soils of the Maritime Antarctic.Proc. NIPR Symp. Polar Biol: 3, 133-150.
References
{{Commonscat Phosphate minerals Orthorhombic minerals Minerals in space group 32 Potassium minerals Aluminium minerals