Jun 3 2014
The term Halotrichite was derived from the Latin word halotrichum, meaning hair salts, as this mineral has a hair-like appearance. It belongs to the halotrichite group.
Properties of Halotrichite
The following are the key properties of Halotrichite:
- Cell Data
- Space group: P21/c
- a = 6.1954(7)
- b = 24.262(3)
- c = 21.262(2)
- β = 100.30(1)°
- Z = 4
- Crystal Data
- Monoclinic
- Point group: 2/m
- As acicular crystals (very rarely terminated), elongated along [001], to 1cm
- As bestiform in divergent or matted aggregates
- As incrustations and efflorescences
- X-ray powder pattern: 4.78 (100), 3.484 (75), 6.02 (35), 4.29 (31), 3.751 (27), 4.93 (21), 3.947 (21)
- Chemical Composition
| Elements |
Content 1 |
Content 2 |
| SO3 |
35.39 |
35.97 |
| H2O |
- |
44.51 |
| H2O- |
30.3 |
- |
| H2O+ |
13.48 |
- |
| Al2O3 |
10.61 |
11.45 |
| FeO |
9 |
8.07 |
| Fe2O3 |
0.22 |
- |
| MgO |
0.13 |
- |
| MnO |
0.05 |
- |
| Na2O |
0.05 |
- |
| K2O |
0.02 |
- |
| Total |
99.25 |
100 |
- Optical Properties
- Optical class: Biaxial (–)
- Orientation: Y = b; Z ^ c = 38°; α = 1.480; β = 1.486; γ = 1.490
- 2V (meas.) = 35°
- Estimated Properties
| Electron density |
Bulk density (electron density) = 2.03 gm/cm3
note: Specific gravity of halotrichite = 1.95 gm/cm3 |
| Photoelectric |
PEHalotrichite = 2.92 barns/electron
U = PEHalotrichite x ρElectron density = 5.93 barns/cm3 |
| Fermion index |
Fermion index = 0.0027453011
Boson index = 0.9972546989 |
Radioactivity
|
Halotrichite is not radioactive
|
How to Identify Halotrichite
Halotrichite can be identified in the field by its uneven, fractured surface and fibrous crystals. It occurs in a range of colors, from colorless to white, gray-white, yellow, and green. It has indistinct cleavage and a semi-transparent form. Its encrustations are crust-like aggregates on matrix. The mineral has a silky lustre, with a white streak, and without fluorescence.
The density range of halotrichite is 1.78 to 1.9, with a hardness of 1.5 to 2 – between talc and gypsum.
Global Distribution
Halotrichite is widely distributed around the world in small quantities. The key locations are listed below:
- Hungary - Kozepso-Gyorgy mine, Recsk, Matra Mountains
- Sweden – Falun
- Italy - Solfatara di Pozzuoli, Campi Flegrei, near Naples, Campania
- Germany - Feengrotten, near Saalfeld, Thuringia
- France - Huelgoat and Poullaouen, Finistere
- USA - Alum Mountain district, Grant Co. New Mexico; Sulfur Hole prospect, near Borate, about 10km north-east of Yermo, Calico Hills, San Bernardino Co. and at hot springs around Mt. Lassen, Shasta Co. California; Dexter No. 7 mine, Calf Mesa, San Rafael district, Emery Co. Utah
- Chile - Tierra Amarilla, south-east of Copiapo, Atacama; Alcaparrosa, near Cerritos Bayos, south-west of Calama, and from Chuquicamata, Antofagasta
- Russia - volcanoes on the Kamchatka Peninsula
- Canada - Glace Bay coal deposits, Nova Scotia
Occurrence of Halotrichite and Useful Mineral Association
Halotrichite occurs as efflorescence in weathering sulfide deposits, and oxidizing pyritic coals, with perpetual build-up in arid climates. It also occurs as a precipitate in the areas around volcanic fumaroles and hot springs.
It is often associated with minerals such as gypsum, epsomite, melanterite, copiapite, and alunogen.
References
http://webmineral.com/data/Halotrichite.shtml
http://www.mindat.org/min-1809.html
http://rruff.geo.arizona.edu/doclib/hom/halotrichite.pdf