Ulrichite, Lake Boga, Victoria

Mineral Matters #413

This week’s Facebook Mineral of the Week Group’s selected theme is uranium minerals.

Ulrichite is a copper calcium uranium phosphate, first found by members of the Bendigo Gem Club (Victoria, Australia) in the mid1980s and submitted to Museum Victoria as an unknown green fibrous mineral. It occurs in one fairly small area of the Lake Boga granite in the quarry, known colloquially as “ulrichite corner”. Many of the other phosphate species also occurred in this spot, although many were more widespread. It was named after George Ulrich (1830-1900) in recognition of his contribution to the description of minerals in Victoria. It has to date not been found anywhere else.

For the most part, ulrichite occurs as opaque pale apple green crystals, occasionally brighter green, or rarely transparent. Under certain lights, they can sometimes have a bluish tinge. Crystals are generally small, and occur as sprays of acicular crystals. Ulrichite formed around 775,000 years ago. It can occur either on its own, or associated with a range of other phosphates including turquoise/chalcosiderite, libethenite, pseudomalachite, crandallite, cyrilovite, saléeite, torbernite, very rarely sampleite, and other species.

Below: Sampleite (blue bladed crystals), pseudomalachite (blue-green blob in the middle), and ulrichite (apple-green acicular crystals), in a void that would have originally been a fluorapatite crystal, Lake Boga, Victoria. Width of view 3.5mm.