Pyrite concretion (unusual form - rare locale)

Item Description

A really unusual looking and rare pyrite concretion from this obscure Newfoundland locale. The oval layered concretion has two strikingly different overgrowths of octahedral pyrite crystals. The cluster at the top and on one side has larger octos, while the strange looking rounded cluster on the other side looks like a flower corsage. One theory of formation is that these are sedimentary exhalative deposits (SedEx deposits). These are ore deposits which are interpreted to have been formed by release of ore-bearing hydrothermal fluids into a water reservoir (usually the ocean). Ore genesis is varied in SedEx deposits and can include black smokers found in mid-ocean ridges and volcanic island arcs. The concretions weather out of matrix and then are rounded by wave action. A fascinating, weird-looking and rare concretion.