Editorial Feature

Biphosphammite - Occurrence, Properties, and Distribution

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Jun 11 2014

Biphosphammite is a tetragonal-scalenohedral mineral, containing potassium, phosphorus, oxygen, nitrogen, and hydrogen.

The mineral was first discovered in 1870 from the Guanape Island, south of Trujillo in Peru. It was considered as a biphosphate of ammonium, and hence derived its name.

Properties of Biphosphammite

The following are the key properties of Biphosphammite:

Cell Data
- Space Group: I42d
- a = 7.4935(5)
- c = 7.340(3)
- Z = [4]

Crystal Data
- Tetragonal
- Point Group: 42m
- As crystals, to 2mm, tapering, prismatic, in radiating groups; stalactitic and in crusts; fine granular, powdery
- X-ray Powder Pattern: 3.75 (10), 5.24 (9), 3.02 (9b), 1.993 (8), 2.650 (7), 2.368 (7), 1.593 (6)

Chemical Composition

Elements	Content 1	Content 2
P₂O₅	51.1	56.52
K₂O	14.2	18.76
(NH₄)₂O	12.3	10.37
SO₃	5.59	-
H₂O	-	14.35
insol.	0.81	-
Na₂O	0.16	-
rem.	16.14	-
Total	100.3	100.0

Optical Properties
- Optical Class: Uniaxial (–)
- ω = 1.525
- ε = 1.480

Estimated Properties

Electron density	Bulk density (electron density) = 2.10 g/cm³ note: Specific gravity of Biphosphammite = 2.04 g/cm³
Photoelectric	PE_{Biphosphammite} = 2.06 barns/electron U = PE_{Biphosphammite} x ρ Electron density = 4.33 barns/cm³
Fermion index	Fermion index = 0.08 Boson index = 0.92
Radioactivity	Biphosphammite is barely detectable

How to Identify Biphosphammite

Biphosphammite is either colorless, brown, or gray-white in color. It has a transparent to translucent appearance, white streak, and vitreous luster.

The density of the mineral is 2.04 g/cm³, and its hardness ranges from 1 to 2.

Global Distribution

Biphosphammite is distributed in the following places:

Guanape Island, south of Trujillo, Peru
Murra-el-elevyn Cave, Cocklebiddy, and in Petrogale Cave, near Madura, Western Australia
Gcwihaba Cave, 280km west of Maun, north-western Botswana

Occurrence of Biphosphammite and Useful Mineral Association

Biphosphammite occurs as an alteration product of phosphammite in guano, due to the loss of NH4, and as a by product of the reaction between the liquid fraction of bat guano and urea.

It is closely associated with syngenite and phosphammite.

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