Sphalerite

This fine specimen of crystalised Sphalerite is obviously very old judging by the unprovenanced label glued to its base; an oval label with a magenta outer double ring and the handwritten number 56/72.  The sphalerite is iron-rich based on its black appearance, although where crystals thin along their edges, translucent shots of reddish clove-brown appear when back-lit.  Individual crystals range from about 1 to 3 mm, but develop to form composite crystals of about, say, 1 to 2 cm wide.  The flat base reveals an inner core of micro-crystalline light grey Quartz mixed with granular Sphalerite and iron-stained orange-tan in places.  A good historic Sphalerite from Cumbria.