Jun 13 2014
Adamite was named after Gilbert-Joseph Adam, a French mineralogist, who provided the first specimens. It is a zinc arsenate hydroxide mineral.
Properties of Acanthite
The following are the key properties of adamite:
- Cell Data
- Space group: Pnnm
- a = 8.304–8.386
- b = 8.524–8.552
- c = 6.036–6.058
- Z = 4
- Crystal Data
- Orthorhombic
- Point group: 2/m2/m2/m
- Elongated along [001], [010], rarely [100], to 8cm, may be equant; dominant {101} and {110}, with {011}, {210}, {010}, {120}, many other forms, usually in radial aggregates, fanlike rosettes, or crystalline crusts
- X-ray powder pattern: 2.448 (10), 4.897 (9), 2.967 (9), 2.698 (8), 1.608 (8), 5.944 (6), 4.242 (6)
- Chemical Composition
| Elements |
Content 1 |
Content 2 |
| ZnO |
56.78 |
56.78 |
| As2O5 |
38.96 |
40.08 |
| H2O |
3.53 |
3.14 |
| SiO2 |
0.26 |
- |
| Total |
99.53 |
100.00 |
- Optical Properties
- Transparent to translucent
- Optical class: Biaxial (+)
- Pleochroism: In pale colors if cuprian or cobaltian
- Orientation: X = a; Y = c; Z = b
- Dispersion: r < v or r > v, strong
- α = 1.708–1.722; β = 1.734–1.744; γ = 1.758–1.773
- 2V(meas.) = 78°-90°
- Estimated Properties
| Electron density |
Bulk density (electron density) = 4.16 g/cm3
note: Specific gravity of Adamite = 4.45 g/cm3. |
| Photoelectric |
PEAdamite = 41.42 barns/electron
U = PEAdamite x ρelectron density = 172.31 barns/cm3 |
| Fermion index |
Fermion index = 0.01
Boson index = 0.99 |
Radioactivity
|
Adamite is not radioactive
|
How to Identify Adamite
Adamite can be identified in the field by its color variations, such as yellow, green, yellowish-green, violet, and pink. It is sub-transparent, and has {101} good, {010} poor cleavage. This mineral has a vitreous–resinous luster, with white streak. The fracture on this mineral is brittle - displayed by glasses and most non-metallic minerals.
The density of adamite is 4.3 to 4.5 g/cm3, with a hardness of 3.5 - approximate to a copper penny.
Global Distribution
Adamite is distributed in the following places:
- Chile – From Chanarcillo, south of Copiapo, Atacama
- Greece - In the Kamariza mine, Laurium
- Namibia - Large crystals from Tsumeb
- Mexico - Large crystals at the Ojuela mine, Mapimi, Durango; in the Hidalgo mine, Zimapan, Hidalgo; and from Santa Eulalia, Chihuahua
- France - At the Cap Garonne mine, near le Pradet, Var
- Germany - From Reichenbach, near Bensheim, Hesse, and in the Clara mine, near Oberwolfach, Black Forest
- England - From several places in Cornwall, and at Caldbeck Fells, Cumbria
- USA - At Gold Hill, Tooele Co. Utah, and in the Mohawk mine, Clark Mountains, San Bernardino Co. California
- Australia - At the Puttapa zinc mine, near Beltana, and on Mt. Painter, Flinders Ranges, South Australia
Occurrence of Adamite and Useful Mineral Association
Adamite occurs in a secondary mineral in the oxidized zone of zinc, and arsenic-bearing hydrothermal mineral deposits.
It is often associated with minerals such as smithsonite, olivenite, quartz, scorodite, hemimorphite, calcite, and Fe–Mn oxides.
References