Chain Silicate

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Minerals composed of chains of silicon tetrahedra. These minerals are divided into single chain and double chain silicates. The former include pyroxenes and pyroxenoids and consist of linked (SiO4)4– tetrahedra each sharing 2 oxygens with its neighbors. Double chain silicates comprise the amphibole group and consist of two tetrahedral chains cross-linked by bridging oxygens. The cleavages are different, reflecting differences in underlying chain structures.

Generally, chemically similar pyroxenes and amphiboles have similar color, luster and hardness. However, amphiboles have (OH) groups in their structures, which are lacking in pyroxenes, resulting in lower densities and refractive indices than pyroxenes with similar cation proportions.

Some or all content above used with permission from J. H. Wittke.

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