Cassiterite pseudomorph after Orthoclase

Wheal Coates at St Agnes in Cornwall is world famous for two things: its magnificent cliff-top engine house set against the backdrop of the Atlantic Ocean and its cassiterite pseudomorphs after Orthoclase feldspar. You need to visit the location to enjoy the former but we can supply the latter! This small miniature, perhaps more accurately a thumbnail, might be small, but it is perfect and a remarkably fine example. Dark brown granular Cassiterite completely replaces a Carlsbad twinned Orthoclase crystal measuring to 2.4 cm. Such Wheal Coates pseudomorphs range from almost entirely Orthoclase speckled with pinhead patches of Cassiterite to complete replacements, this charming example being the latter. It is accompanied with the previous collector’s label, one of the UK’s most highly respected; the collector that is, not the label!