Editorial Feature

Okenite – Occurrence, Properties, and Distribution

May 7 2013

Okenite is a silicate mineral that resembles small white ‘cotton balls'. It is found within basalt geodes. The mineral was named after Lorenz Ocken, a German naturalist from Munich, Germany. It was discovered in 1828.

Properties of Okenite

The following are the key properties of okenite:

Cell Data
- Space group: P1
- a = 9.69(1)
- b = 7.28(1)
- c = 22.02(4)
- a = 92.7(2)°
- β = 100:1(3)°
- = 110:9(1)°
- Z = [2]
Crystal Data
- Triclinic
- Point group: 1
- As bladed crystals, basically fibrous with [010] as fiber axis
- Aggregates of curved crystals
- Compact radial fibrous balls, to 4 cm
- Twinning: About [010], composition plane {102}, lamellar
- X-ray powder pattern: 21 (vvs), 8.8 (vs), 3.56 (vs), 2.93 (vs), 3.07 (s), 3.05 (s), 2.98 (ms)

Chemical Composition

Elements	Content 1	Content 2
SiO₂	53.88	53.88
CaO	27.61	28.51
H₂O	18.02	16.49
SrO	0.27	-
Na₂O	0.12	-
Al₂O₃	0.08	-
K₂O	0.06	-
Fe₂O₃	0.01	-
Total	100.05	100.00

Optical Properties
- Optical class: Biaxial (-)
- α = 1.530
- β = 1.536
- γ= 1.541-1.553
- 2V (meas.) = Large

Estimated Properties

Electron density	Bulk density (electron density)=2.35 gm/cm³ note: Specific gravity of okenite =2.32 gm/cm³
Photoelectric	PE_Okenite = 3.48 barns/electron U=PE_Okenite x ρElectron density= 8.20 barns/cm³
Fermion index	Fermion index = 0.01 Boson index = 0.99
Radioactivity	Okenite is not radioactive

How to Identify Okenite

Okenite can be identified in the field by its white, yellowish white, and bluish white variations. The mineral has good cleavage in a semitransparent non-fluorescent form. It has conchoidal-fractures with thin thread-like capillaries. The crystals are fibrous and spherical. This mineral has a pearly lustre with white streak. The density of okenite is 2.3-2.33 g/cm³with a hardness of 5 -approximate that of apatite.

Global Distribution

Okenite is found in the following locations:

India – Syhadree Mountains and Bombay quarry, Maharashtra; Poona; Nasik; Kolhapur district
Chile - Rio Putagan
Greenland - Qutdligssat (Kudlisat), Ritenbenk district; Qeqertarsuaq Island; Skarvefjeld and Blæsedal, Godhavn district
Canada - Jeffrey mine, Asbestos, Quebec
Faroe Islands - Bordoy and Streymoy
Ireland - Scawt Hill, near Larne, Co. Antrim
Scotland- Isle of Mull and Morven Peak, Grampian Highlands
Mexico - Noche Buena mine, Mazapil, Zacatecas
USA - Crestmore, Riverside Co., California; Fairfax quarry, Centreville, Fairfax Co., Virginia; Skookumchuck Dam, near Bucoda, Thurston Co., Washington

Occurrence of Okenite and Useful Mineral Association

Okenite occurs commonly in amygdules in basalts. It is often associated with minerals such as zeolites, prehnite, calcite, apophyllite, quartz, and chalcedony.