Spodumene : LiAlSi2O6, Muscovite : KAl2(AlSi3O10)(OH)2, Albite : NaAlSi3O8

minID: 5T3-TMD

Spodumene : LiAlSi2O6, Muscovite : KAl2(AlSi3O10)(OH)2, Albite : NaAlSi3O8

This is a 12 cm spodumene pseudomorph completely replaced by greenish muscovite from the Maine Feldspar Quarry. Field view is 17 cm. Collected by Doug Watts in 1995.

This specimen is from a unique section of the MFQ pegmatite where every mineral was completely replaced by greenish fine-grained and pseudohexagonal muscovite. I'm provisionally calling the large replaced crystal spodumene due to its flat cleavage and square cross-section. The next most likely mineral would be schorl, but the lath-like cleavage, still visible in the pseudomorph, is diagnostic against schorl and more favorable to spodumene. The albite in the matrix appears to have been completely re-crystallized to the consistency of table sugar.

This entire class of goofy pseudomorphs are characterized by late stage epitaxial growths of snow white albite, 1-2 mm clear quartz crystals variably coating surfaces and fissures, and fairly abundant large clear, milky and smoky quartz crystals. The 'honker' complex quartz xls were mostly removed from the pseudomorph matrix by collectors in the 1960s, acc. to Ray Woodman. They left the pseudomorphs behind. As far as the honkers go, it's hard to tell if they were formed originally or were part of the late quartz muscovite replacement, since many of them also look as if they were attacked as well.

This is part of a photo suite I'm working on to document the unique character of this late stage replacement unit at the MFQ pegmatite.

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Photo added: 22nd Jul 2012

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