Pyrrhorite - Magnetic Pyrites Composition, Crystallization and Structure

Composition. A ferrous sulphide contaning variable amounts of dissolved sulfur and so varying in composition from Fe₅S6 up

To Fe₁₆S₁₇. Fe₁₁S₁₂ is the usually accepted formula. Often carries a small amount of nickel.

Crystallization. Hexagonal. Crystals usually tabular, or sometimes pyramidal. Structure. Practically always massive with granular of lamellar structure.

Physical Properties. H. = 4. G. = 4.65. Metallic luster. Brownish bronze color. Black streak. Usually slightly magnety magnetic, but sometimes scarcely at all so.

Tests. Esily fusible. Strongly magnetic after heating. B. B. or in O. T. gives odor of sulfur dioxide. Little or no sulfur in C. T. Decomposed by hydrochloric acid, giving off hyfrogen sulphide gas. Recognized usually by its massive structure and bronze color.

Occurrence. A common minor constituent of igneous rocks. Occurs in large masses in intimate association with basic igneous rocks from which it ha been segregated by some form of magmatic differentiation. Associated with the ferrmagnesisn minerals of the rocks in which in occurs, and also with chalcopyrite, and nickel minerals, as pentlandite, millerite, etc. It is also found in contact metamorphic quantities in Norway and Sweden, at Sudbury, Ontario, Canada. In Germany from Andreasberg in the Harz Mts., at Schneeberg, Saxony; Bodenmais, Bavaria. In the United States in crystasl form Standish, Maine; was found at the Gap Mine, Lascaster county, Pensylvania; in considerable amount at Duck town, Tennessce.

Name. derived from a Greek work meaning reddish.

Use. Serves as an important ore of nickel, particulary at Sudbury, Ontario

In this group belongs also the rare mineral, wurtzite, ZnS, which differs from sphalerite, since it is hexagonal in crystallization.