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Boracite with Anhydrite

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Boracite is a rare magnesium borate chloride mineral found in certain unusual evaporite deposits, one of which is the ancient Zechstein Sea that dried out 250 million years ago. However, even when it does occur crystals are usually in the millimetre scale and as loose individual crystals dissolved out from matrix. This superb crystallized specimen is from the amazing systematic collection assembled by brothers Martin and Michael Günther (1951-2007 & 1956-2021) and displays two extremely large, highly modified pseudocubic to perhaps dodecahedral crystals of Boracite embedded in white Anhydrite matrix. The largest is about 1 cm across and the smaller one not much less than that. It is from the Lüneburg area in Lower Saxony, Germany, where this species was first described nearly two centuries ago and where the Boracite is nearly always pale grey in colour. Those familiar with Boracite will know that Boulby potash mine in northern England mines the other end of Zechstein Sea evaporite beds out underneath the current North Sea and has produced fine pale blue Boracite, but never in crystals the size as these from Lüneburg. This is a significant example for the size of crystals and the fact that they are on matrix.