Editorial Feature

Algodonite - Occurrence, Properties, and Distribution

Jun 4 2014

Algodonite is a gray-white metallic, copper arsenide mineral, crystallizing in a hexogonal pattern. The mineral was first discovered from the Algodones silver mine in Coquimbo, Chile in 1857.

It has a Mohs hardness of 4, and a specific gravity of 8.38 to 8.72.

Properties of Algodonite

The following are the key properties of Algodonite:

Cell Data
- Space Group: P63/mmc
- a = 2.600
- c = 4.228
- Z = 2

Crystal Data
- Hexagonal
- Point Group: 6/m 2/m 2/m
- As incrustations of minute highly distorted crystals; commonly massive and granular
- X-ray powder pattern: 1.989 (100), 2.11 (40), 2.25 (20), 1.299 (20), 1.194 (20), 1.110 (20), 0.837 (20)

Chemical Composition

Elements	Content 1	Content 2	Content 3
Cu	83.11	83.53	83.58
As	16.44	16.55	16.42
Ag	Trace	-	-
Total	99.55	100.08	100.00

Optical Properties
- Opaque
- Color: Steel-gray to silver-white, tarnishes dull on exposure; in polished section, bright cream-white.
- Luster: Bright metallic
- Anisotropism: Weak

Estimated Properties

Electron density	Bulk density (electron density) = 8.33 g/cm³ Note: Specific gravity of Algodonite = 9.18 g/cm³
Photoelectric	PE_Oligoclase = 50.32 barns/electron U = PE_Oligoclase x ρElectron density = 419.22 barns/cm³
Fermion index	Fermion index = 0 Boson index = 1
Radioactivity	Algodonite is not radioactive

How to Identify Algodonite

Algodonite can be identified in silver-white or steel-gray color forms. This mineral is opaque and non-fluorescent in nature. It has metallic lustre and nonmagnetic properties. Sub-conchoidal fractures are developed in brittle materials, having semi-curving surfaces. It forms massive granular crystals, commonly observed in granite or other igneous rock.

It has an average density of 8.55 g/cm³, and a relative hardness of 4.