Editorial Feature

Taranakite – Occurrence, Properties, and Distribution

Taranakite is a hydrated alkali iron-aluminium phosphate mineral. The mineral was named after the place it was first discovered- Taranaki Peninsula, New Zealand.

Properties of Taranakite

The following are the key properties of taranakite:

  • Cell Data
    • Space group: R3c (synthetic)
    • a = 8.7025(11)
    • c = 95.05(1)
    • Z = 6
  • Crystal Data
    • Hexagonal
    • Point group: 3 2/m
    • Pseudohexagonal platy crystals- rarely to 0.5 mm and typically in compact nodular aggregates, pulverulent, powdery, flourlike to claylike massive
    • X-ray powder pattern: 15.82 (100), 3.82 (40), 3.14 (31), 3.36 (29), 7.47 (28), 3.59 (22), 7.92 (18)
  • Chemical Composition
    Elements Content 1 Content 2 Content 3
    P2O5 42.32 41.88 42.30
    H2O 31.10 28.43 28.18
    Al2O3 19.03 17.48 18.99
    K2O 7.09 8.43 10.53
    Fe2O3 0.42 1.67 -
    Na2O - 1.28 -
    Insol. - 0.37 -
    Total 99.96 99.54 100.00
  • Optical Properties
    • Optical Class: Uniaxial (–)
    • ω = 1.506–1.510
    • ε = 1.500–1.503
  • Estimated Properties
    Electron density Bulk density (electron density)= 2.19 g/cm3
    note: Specific gravity of taranakite = 2.15 g/cm3
    Photoelectric PETaranakite = 2.09 barns/electron
    U=PETaranakite x ρelectron density= 4.58 barns/cm3
    Fermion index Fermion index = 0.000301283
    Boson index = 0.999698717
    GRapi = 128.51 (Gamma Ray American Petroleum Institute Units)
    Taranakite is radioactive (barely detectable)

How to Identify Taranakite

Taranakite can be identified in the field by its gray white, yellowish white, or white color variations. The appearance of this mineral is transparent. It is a non-fluorescent mineral with a white streak. The density of taranakite is 2.09 g/cm3 and hardness is 1-2 - between talc and gypsum.

Global Distribution

Taranakite is widely distributed in the following locations:

  • New Zealand - From the Sugarloaves, near New Plymouth, Taranaki Peninsula
  • Argentina - Island Leones, Patagonia
  • On R´eunion Island, Indian Ocean
  • King George Island, Maritime Antarctic
  • Australia - in the Russenden Cave, Queensland; the Skipton lava tube caves, southwest of Ballarat, Victoria; in caves at Mimegarra, Western Australia; and the Jenolan Caves, New South Wales
  • Malaysia - From the Niah Great Cave, Sarawak
  • Japan - In the Onino-Iwaya Cave, Hiroshima Prefecture
  • South Africa - In Etienne’s Cave, and well-crystallized in Christmas Cave, Transvaal Bulgaria - From the Bacho Kuo Cave
  • China - In the Yangsue Posayen Cave, 20 km south of Guilin, Guangxi Province
  • France - In the Minerva Grotto, Fauzan, H´erault
  • Algeria - From the Tour Combes Cave, near Oran
  • USA - in the Pig Hole Cave, Giles Co., Virginia; and the Low Water Bridge Cave, Greene Co., Missouri
  • Italy - in the Castellana Cave, south of Bari, Puglia; on Monte Alburno, near Controne, Salerno.

Occurrence of Taranakite and Useful Mineral Association

Taranakite is often associated with minerals such as ardealite, vashegyiteminyulite, francoanellite, leucophosphite, brushite, strengite, variscite, and vivianite. Taranakite is formed from phosphatic solutions derived from bird or bat guano reacting with clays or aluminous rocks under perenially damp conditions. It is the most common phosphate mineral found in caves.


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