Manganaxinite, Johannsenite xls; Iron Cap Mine, Arizona, USA; 1 flat

Mangan-Axinite and Johannsenite crystals from the Iron Cap Mine in Arizona, USA. 1 flat

This flat contains multiple representative specimens with crystalline Mangan-Axinite and embedded to exposed Johannsenite. The Mangan-Axinite crystals mostly appear as brown-violet, highly lustrous lamellae in parallel groups, while the Johannsenite shows as fibrous to acicular greenish-black aggregates. Both minerals are distinctly developed on a light grey to greenish matrix.

Geology & Origin

The Iron Cap Mine in Arizona is known for its complex skarn-type deposits, where rare silicates such as Mangan-Axinite and Johannsenite occur together. Mangan-Axinite forms in contact zones between igneous rocks and carbonate sediments under hydrothermal conditions. Johannsenite forms in similar settings and is paragenetically associated. The presented specimens are typical representatives of this paragenesis and originate from older mining phases at the locality.