Bertrandite from Mount Antero, Colorado

S. L. Penfield
1888 American Journal of Science  
THIS rare mineral was first identified as a new species by M. E. Bertrand * from the study of a few small crystals collected from a pegmatite vein at Petit Port, near N antes, France. M. Des Oloizeauxt has also identified the mineral at the gneiss quarries at Barbin, near Nantes, while M. A. Damonr:j: has analyzed it and determined its composition to be H.Be.Si.O.; he also gave to it the name Bertrandite. The mineraI has since been identified by R. Scharizer § at a feldspar quarry near Pisek,
more » ... uarry near Pisek, Bohemia, where" it occurs lining cavities left by the decomposition and disappearance of beryl crystals. At all of these localities the crystals ate minute and are found only in small quantities. The crystalline form determined by Bertrand and Des Oloizeaux is orthorhombic, while Scharizer finds grounds for believing that the crystals are monoclinic with close approximation in form and optical properties to orthorhombic symmetry. The single hand-specimen in the author's possession was selected by Mr. W. B. Smith, of Denver, 001., from a lot of material collected during the past summer at Mt. Antero in the search for specimens of phenacite. The crystals of bel'trandite are attached to quartz which is associated with beryl.
doi:10.2475/ajs.s3-36.211.52 fatcat:cv2snra55nbrdlhqhgdniuamje