Dims: 7.0" x 5.4" x 0.1" (17.8 x 13.7 x 0.2 cm)
Wt: 3.67 oz. (104.0 g)
Minas Gerais, Brazil
This odd specimen consists of a single large "book" of Muscovite. It shows a warped but complete pseudohexagonal form, and some of its edges are truncated by angled faces that have a very strange texture; they almost seem as if they had been ground down with a sanding belt or a grinding wheel, but such actions would have made the surfaces disseminate, bend, and flake. It has the standard pale brown color, pearly luster, and micaceous consistency that one expects of Muscovite and shows a very dim but noticeable transparence. What drew us to this piece is the fact that it has a warped and incomplete crystal of elbaite tourmaline running through half of it! It does show a triangular or hexagonal cross-section, though, and its visible faces are well-defined where intact and show a vitreous luster. In moderate light the crystal appears black and opaque, but in bright light or sunlight one can see its deep blue-green color and some areas of transparence.