Synthesis of pigeonites for spectroscopic studies.

Pigeonite (P2₁/c clinopyroxene) crystallizes in various terrestrial and extraterrestrial rocks. However, because it breaks down ("inverts") in slowly cooled rocks, bulk natural samples of pigeonite from coarse-grained rocks are not available. We have synthesized eight samples of pigeonite with compositions of Wo₈ and Wo₁₀ [where Wo (mol%) = 100Ca/(Ca+Mg+Fe²⁺)] and X ranging from 20 to 60 [where X = 100Fe²+/(Mg+Fe²+)]. These samples are suitable for spectroscopic and other studies that require bulk samples. Because of relatively fine grain size (mainly 5-50 mm) and slight grain-to-grain variation in composition, they are generally not suitable for studies requiring individual crystals. We will make samples available for appropriate investigations, especially if the techniques used are non-destructive and the samples can be returned after use. [ABSTRACT FROM AUTHOR]