HYDROXYLGUGIAITE: A NEW BERYLLIUM SILICATE MINERAL FROM THE LARVIK PLUTONIC COMPLEX, SOUTHERN NORWAY AND THE ILIMAUSSAQ ALKALINE COMPLEX, SOUTH GREENLAND; THE FIRST MEMBER OF THE MELILITE GROUP TO INCORPORATE A HYDROGEN ATOM

摘要

Hydroxylgugiaite, ideally (Ca-3 square(1))Sigma(4)(Si3.5Be2.5)Sigma O-6(11)(OH)(3), is a new mineral species from two localities in the Larvik plutonic complex in Porsgrunn, Telemark, Norway, and one locality in Ilimaussaq, Greenland. Hydroxylgugiaite crystals occur as squat dipyramids {111} (30 3 50 mu m) or as elongate tetragonal prisms. The crystals are translucent, white to pale grey in color, with a white streak and vitreous luster. It is brittle, with no apparent cleavage. Hydroxylgugiaite is uniaxial positive with omega= 1.622 +/- 0.002 and epsilon=1.632 +/- 0.002. There is no pleochroism and birefringence is low.