Tetrahedrite and Pyrite with Calcite - rare locale

Item Description

Fascinating and intricate, this Scottish (Loch Tay actually spans the Sterlin/Perth and Kinross border, with localities on each side) combination piece clearly has a complex history whose details really aren't all that clear. Looking at this piece, the overall cubic shape immediately jumps out at you, so logically you would expect the large, primary Pyrite to be solid. But it's not! Rather, it is composed of hundreds to thousands of small, lustrous Pyrite crystals. And then nestled back in the inside corner is a 2 cm cluster of smaller Tetrahedrite crystals. But are all those Pyrites pseudomorphed after a large single crystal, or is this a cast after something else, or an epimormorph around the Tetrahedrite? The only thing we know for sure is that the associated Calcites came last. Recently deaccessed from the Tim Sherburn collection.