Cuprosklodowskite Uranium minerals are often colourful,…


Uranium minerals are often colourful, especially the secondary ones formed by alteration of primary deposits by water. This one forms when deposits also containing copper, and is found in the Katanga copper belt in the Democratic Republic of Congo. It is a hydrated copper uranium silicate and usually forms in sprays of small crystals. This mineral is highly radioactive, and special storage in a lead lined container is recommended, and limited handling advised. It should also be stored away from other minerals as its radiation may affect their colour. It was named after radiation researcher Marie Curie, whose Polish birth name was Sklodovska (with the l pronounced W).

This example measures 12x8x6cm, and the green radial puffballs of cuprosklodovskite are dusted with yellow crystals of another uranium mineral called guillemite.


Image credit: Rob Lavinsky/

The Alma QueenThe world’s finest rhodochrosite crystal…

The Alma Queen

The world’s finest rhodochrosite crystal lives at the Houston Museum of Natural Sciences. Extracted in 1965 from a pocket at the Sweet Home mine in Colorado the main crystal us 10 cm across and of exceptional colour. The matrix is quartz and tetrahedrite, and the specimen is one of the most famous and photogenic in the world of mineralogy.

Image credit: Houston Museum of Natural Sciences