Mineral: Baryte
Locality: Clara Mine, Rankach Valley, Oberwolfach, Wolfach, Black Forest, Baden-Württemberg, Germany
Dimensions: 14,4 x 12,3 x 10,2 cm

Description: Grube Clara is not only famous for the remarkable number of different mineral species that have been found over the years, it has also produced an astonishing variety of baryte specimens. This diversity, both in species and baryte habits, can be attributed to three main consecutive phases of hydrothermal activity. The baryte from this first period is known as 'Messerspat', or 'knife spar', and is easily distinguished by the thin white tabular habit. In later hydrothermal phases, this primary baryte partially dissolved and was redeposited as 'Honigspat' and 'Meißelspat' respectively. The former, 'honey spar', is characterised by the yellow colour reminiscent of honey. The latter, 'chisel spar', is usually clear, although it very often displays brown, orange and yellow phantoms and appears in a multitude of different habits. This specimen shows a relatively rare example in which all three types are present. The white matrix consists of the first phase, showing the tabular habit in the cross section (although no complete crystals are present). This is covered by more blocky yellow baryte from the second phase, that partially shows parallel growth to the first generation. The second baryte layer has been covered by black manganese oxides, before the third generation of baryte grew on top of it all. The third generation features the largest crystals, ranging from clear to orange due to inclusions. This very distinctive habit is sometimes referred to as 'Walmdach'-habit, as they resemble the shape of the roofs of the vernacular Black Forest farm houses. Some empty space can be observed in places between the second and third generations, indicating that some other mineral or pocket clay has been dissolved away. Finally, some of the third generation crystals also show marks where their growth was impeded by a now disappeared mineral.

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