Niahite

Cave Name:

Niah Great Cave, Sarawak, Malaysia

Speleothems:

Frequency: Rare

First description of cave occurrence:

Bridge, P.J., Robinson, B.W. 1983. Niahite-a new mineral from Malaysia. Mineralogical Magazine, 47: 79-80.

First description of non-cave occurrence:

Conservation and Protection:

Latitude: 3°48'18'' N

Longitude: 113°46'8'' E

Type of rock:

IMA status: Approved

Group: Phosphates

Chemical formula:
[According to the official IMA-CNMNC List of Mineral Names (http://nrmima.nrm.se/imalist.htm)]

(NH₄)(Mn²⁺,Mg,Ca)PO₄.H₂O

Varieties:

Deposition and stability:

Formed through the decomposition of bat guano and urine. No indications of Mn source.

Habit: Radiating to sub-parallel crystals

Color: Pale orange

Hardness: Not measured

Identified by:

Chemical analysis:

(NH₄)₂O: 12.9; MnO: 27.21; MgO: 4.19; CaO: 1.99; P₂O₅:37.83, H₂O:11.88 (values in %)

Mineral assemblage:

Crystal system:

Cell parameter a (Å): 5.68

Cell parameter b (Å): 8.78

Cell parameter c (Å): 4.88

Crystal size: < 0.5 mm

Polarizing:

Colorless in thin section; Biaxial (-) with 2V = 54º (meas.) and 50º (calc.); Refractive indices are α = 1.582(2); β = 1.604(2); γ = 1.609(2)

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