Biotite with book plate

Unknown Owner

This is a fascinating and extremely unusual combination consisting of a coloured book plate of Mica and Chlorite group minerals from a publication (we believe it to be Das Mineralreich, 1903) by Reinhard Brauns (1861-1937), and a specimen of Biotite from Monte Somma, Naples, Italy, featured in the illustration. The colour plate and caption are mounted on a large sheet of card and there are several old collection labels accompanying it too. Individually, the specimen is very fine too. It is miniature to large miniature in size and dominated by a large open cavity within white to cream coloured matrix. Within the cavity, extremely well defined thin, translucent green, micaceous platy hexagonal crystals of 'Biotite' dominate. They were published within the text as Biotite, but are perhaps more correctly - based on their colour - Phlogopite. It is from the superb systematic collection assembled by the brothers Martin and Michael Günther (1951-2007 & 1956-2021) who were meticulous in keeping all old labels and recording their history. Combinations such as this are extremely rare, as the detective work and good fortune required in matching specimens is immense. A fascinating piece of mineralogical history.