Celestine

It seems like beautiful deep sky-blue Celestine from Madagascar has been around for ever, but it was only first discovered in 1967.  This now makes sense to me why so much of this wonderful material was available in the early 1970s, just as I was getting into minerals.  At Sakoany, the Celestine, a strontium sulphate, is mined from shallow deposits occurring in interbedded crinoidal limestones and sandy greywackes by the local artisan miners.  These mine workings average about 15 m deep and are worked somewhat inland from the original seashore outcrop to avoid water ingress to the workings.  This cabinet specimen is a splendid example of this classic material, displaying mid-sapphire to cornflower-blue crystals to 2 cm around the periphery of this part geode.  Amongst these, in the centre, sits a fabulous 4.5 x 4.5 x 3.5 cm deep cornflower-blue single crystal with crisp sharp edges, mirror-like glassy faces and transparency verging on gemmy.  It is delightful!