Boracite

Boracite, magnesium borate, occurs sporadically in the Permian potash beds in Boulby mine at Loftus near the coastal village of Staithes, North Yorkshire.  Although loved by collectors, it is the scourge of miners as, due to its hardness of 7 to 7.5 it quickly dulls drill bits when encountered!  This great specimen shows both well crystallised Boracite filling the upper vuggy surface and grading to massive Boracite, probably more typical of what is usually present in the mine.  Both the massive and crystalline Boracite is a fairly uniform pale powder sky-blue and the crystals form radiating sprays to around 1 cm across.