2.5 x 2.3 x 2.0 cm. This extremely rare calcium arsenate is reported from only one mine in the world, the type locality at Jachymov (St Joachimsthal), and the label states that it's from the Svornost Mine. The piece features small white triclinic svenekite botryoidal groups on matrix. Best seen under the microscope, but we were able to photograph it with a Canon MP-E 65mm macro lens. This is one of the few pieces this material that we've had, and it is accompanied by a classic label from Czech mineral expert, Josef Vajdák/Pequa Rare Minerals. — Photo: Robert M. Lavinsky · CC BY-SA 3.0
Švenekite
Švenekite is an IMA-recognized mineral species in the arsenate class, with the chemical formula Ca[AsO₂(OH)₂]₂.
It crystallizes in the triclinic crystal system (space group P-1).
Key properties: Mohs hardness 2; specific gravity 3.16; White streak; Vitreous luster.
IMA symbol Švn, IMA status: approved, named in 1999.
A secondary mineral coating granite near a polymetallic hydrothermal vein.
It is found associated with None given.
The mineral was named to honor Dr. Jaroslav Švenek (1927-1994), the former curator of the mineralogical collection of the National Museum in Prague, Czech Republic.