Gem, Rock, and Mineral Postage Stamps Featuring

Rock Name: Anorthosite
Composition: A rock almost entirely composed of plagioclase, a subgroup of the feldspar group of minerals. The plagioclase feldspars form a series from sodium aluminosilicate to calcium aluminosilicate, with the members of the group having varying amounts of sodium and calcium.
Nomenclature: Named after the Greek words an and orthos which mean "not" and "upright" respectively because plagioclase forms obliquely-shaped crystals.
Industrial Uses: Crushed stone, building material.
Additional Notes: Anorthosite is an igneous rock formed beneath the surface of the earth. Its primary constituent, plagioclase, is one of the most common rock-forming minerals.

New Caledonia Scott 473
Anorthosite (Feldspar); Nephrite (Jade); Serpentine
New Caledonia
Scott 473
30 francs
17 Mar 1982

The stamp shows a polished slab of material. Philatelic Mineralogy Copyright © 1997-2010 by Richard Busch