Editorial Feature

Zussmanite - Occurrence, Properties, and Distribution

Jun 3 2014

Zussmanite is a hydrated iron-rich silicate mineral, occurring as pale green crystals with perfect cleavage. It was first discovered by Stuart Olof Agrell in the Laytonville quarry, Mendocino County, California in 1960.

The mineral was named after Jack Zussman, a crystallographer and emeritus professor of geology, Manchester University, England.

Properties of Zussmanite

The following are the key properties of Zussmanite:

Cell Data
- Space Group: R3 or R3
- a = 11.66(2)
- c = 28.69(2)
- Z = 3

Crystal Data
- Hexagonal
- Point Group: 3 or 3
- As tabular crystals, to about 1mm
- X-ray powder pattern: 9.60 (100), 4.78 (45), 3.19 (25), 2.51 (16), 3.78 (10), 2.74 (10), 2.20 (10)

Chemical Composition

Elements	Content 1
O	41.73
Fe	28.61
Si	22.24
Mn	2.56
K	1.82
Al	1.26
Mg	1.13
H	0.66
Total	100

Optical Properties
- Translucent
- Color: Pale green in thin section
- Luster: Vitreous
- Optical Class: Uniaxial (-)
- Pleochroism: Weak
- O = pale green
- E = colorless
- ω = 1.643
- ε = 1.623

Estimated Properties

Electron density	Bulk density (electron density) = 3.09 g/cm³ note: Specific gravity of Zussmanite = 3.15 g/cm³
Photoelectric	PE_Zussmanite = 10.23 barns/electron U = PE_Zussmanite x ρElectron density = 31.62 barns/cm³
Fermion index	Fermion index = 0.01 Boson index = 0.99
Radioactivity	Zussmanite is barely detectable

How to Identify Zussmanite

Zussmanite can be found in a light green color. It has a translucent appearance, with a vitrous luster, and white streak.

The density of zussmanite is 3.146 g/cm³.

Global Distribution

Zussmanite is widely distributed in the Laytonville quarry, Mendocino Co. California, USA.

Occurrence of Zussmanite and Useful Mineral Association

Zussmanite occurs in an exotic block of metamorphosed shales, siliceous ironstones, and impure limestones; probably representing deep ocean sediments subjected to blueschist facies metamorphism.

It is commonly associated with graphite, ferroan kutnohorite, manganoan siderite, aragonite, grunerite, aegirine, quartz, riebeckite, spessartine, stilpnomelane, howieite, and deerite.