Minerals are naturally occurring cristals and therewith chemically and structurally homogenic parts of stones. Minerals can be divided into ten groups, like for example in elements, halogenids or in phosphate.

The Grube Clara in Oberwolfach, source of the stones on the stockpiles, is characterized through its very high variety on minerals, which comprehend more than 400 different minerals. A list of all minerals found in the Grube Clara can be found  here (status of the list: 2021).

Furthermore, the Mineralienatlas gives further information about the most important features of all types of minerals. If you are interested in the beauty of minerals under the microscope, we recommend the following website with a vast variety of Mineralienfotos.


6 examples for minerals of the Grube Clara:

1. Barite

Barite, or also heavy spar, is the most frequently occurring mineral in the Grube Clara and is characterized by its high density. Often barite builds transparent cristals, which can also be coloured in other colours when other minerals has influenced the stone.


Malachite is a mineral of the carbonate class with the chemical composition (Cu[(OH)2(CO3). Malachite forms in the oxidation zone of copper deposits and is therefore a secondary mineral. Its deep to light green color is a key feature of the minerals


Fluorite, or fluorspar, is the calcium salt of hydrofluoric acid and has the chemical composition CaF2 . Pure fluorite is colorless, but its crystals can also change color due to external influences. When irradiated with UV light, fluorite shows strong fluorescence.


Silver is a chemical element and is an easily malleable heavy metal with very high electrical and chemical conductivity. The world's most important silver deposits are found on the American continent, or more precisely in Mexico, the USA, Canada, Bolivia and Peru.


Quartz is the second most common mineral in the earth's crust, has the chemical composition SiO2 and usually has a distinctive crystal structure in various shapes and colors. Quartz is also characterized by its great hardness and its lack of cleavage.


Scorodite is a secondary mineral of the mineral class of phosphates, arsenates and vanadates and is a rather rare mineral. Skorodite is typically found in the oxidation zone of iron and arsenic ore deposits and is therefore found in many locations in Germany (Black Forest, Saxony, Fichtelgebirge...).