Clinoclase

Rare clinoclase on matrix from the world-famous Clara Mine, Oberwolfach, Freiburg Region, Baden-Württemberg, Germany. The specimen shows deep blue to blue-green clinoclase forming well-developed, bladed to acicular crystal aggregates on matrix, displaying the intense colour and vitreous luster characteristic of fine material from this locality.

Clinoclase is a rare arsenate mineral, first described in 1868 and named from the Greek klínein (to incline), referring to its characteristic inclined crystal form. The species predates the IMA system and is therefore regarded as a grandfathered mineral (pre-IMA, no official IMA number assigned). Clinoclase forms as a secondary mineral in the oxidation zone of copper-bearing deposits.

The Clara Mine is one of the most important localities worldwide for clinoclase and other secondary copper arsenates. Clinoclase is considered rare, and well-crystallized blue specimens such as this represent a good and characteristic example for the species. At Clara, clinoclase commonly occurs associated with quartz and secondary copper minerals.

The specimen originates from the former collection of C. Strömpl, an amateur mineralogist.