Mica, Glauconite

This is a sample from a moraine deposit just north of Ingles Creek, Washington State on Highway 90. Its beta and gamma refractive indices are about 1.61 and its 2V is about 15 degrees.

Transmitted Brightfield Illumination

Definition/Function:

Glauconite is a sheet silicate with the general chemical composition indicated as
(K, Ca, Na)_~1.6(Fe³⁺,Al,Mg,Fe²⁺)₄ Si_7.3Al_0.7)O₂₀OH₄. It is a mineral generally formed as a result of marine diagenesis in shallow water.

Significance in the Environment:

Characteristic Features:

Associated Particles:

References:

Deer, W. A., R. A. Howie, and J. Zussman, AN INTRODCUTION TO THE ROCK-FORMING MINERALS, ISBN 0-582-30094-0, pp. 296-297, 1992.