Millerite with Calcite

A rare and relatively rich old-time specimen of Millerite on Calcite from the St. Andreasberg mining district in the Harz Mountains of Lower Saxony, Germany.  The Millerite crystals are very tiny, probably never exceeding  1 mm in length and mainly much shorter.  They form a velvety druse covering a roughly 4 x 2 cm area of Calcite matrix, which in itself has an aged patina.  The Millerite, a nickel sulphide, forms metallic acicular micro hair-like crystals of dull bronze, often with a reddish-purple tarnish.  Greyish-cream hexagonal Calcite crystals to about 4 mm diameter are associated with the Millerite.  The specimen comes with two very old copperplate, handwritten labels.  A particularly rare example of Millerite from St. Andreasberg, a species very seldom encountered even when the mines were operational.