Rare devonian age pyrite concretion - nodule from dolomite quarry !

Description

Specimen:
Rare devonian age pyrite concretion - nodule from
dolomite quarry.
Locality:
Poland,
Holy Cross Mountains,
Kowala
Stratigraphy:
Devonian - Famennian
Age:
ca. 370 - 360 Mya
Matrix size :
ca. 3,5 x 3,0 x 1,3 cm
( white square on pictures is 1,0 x 1,0 cm )
Description:
Rare devonian age pyrite concretion - nodule from
dolomite quarry.
An interesting, rarer way of occurrence of this mineral.
Pyrite usually forms cuboid crystals, sometimes forming in close association to form raspberry-shaped masses called framboids. However, under certain circumstances, it can form anastamozing filaments or T-shaped crystals. Pyrite can also form almost perfect dodecahedral
shapes known as pyritohedra and this suggests an explanation for the artificial geometrical models found in Europe as early as the 5th century BC.