Grumiplucite, a new mercury-bismuth sulfosalt species from the Levigliani mine, Apuan Alps, Tuscany, Italy

Grumiplucite, ideally HgBi2S4, is a new mercury - bismuth sulfosalt species . It occurs as submillimetric prismatic, grey-black metallic crystals, toge ther with mercury, cinnabar and mercurian sphalerite, in cavities of quartz - carbonate veins in the small mercury deposit of Levigliani, Apuan Alps, Tuscany, Italy. Crystals are elongate according to [010] axis and ubiquitou sly twinned on (001). Grumiplucite has a monoclinic symmetry, space group C 2/m, with unit-cell dimensions a 14.164(5), b 4.053(1), c 13.967(3) Angstro m, beta 118.28(3)degrees V 706.1(6) Angstrom(3), Z = 4. The strongest five reflections of the X-ray powder-diffraction pattern [d in Angstrom(I)] are: 3.05(s), 2.914(ms), 2.865(ms), 3.86(m), and 3.55(m). Grumiplucite is the n atural analogue of the synthetic compound HgBi2S4. In reflected light, it i s creamy white (parallel polars) with low bireflectance; under crossed pola rs, the mineral is distinctly anisotropic (bluish grey to yellowish grey). The calculated density is 7.02 g/cm(3). It formed at a low temperature in a low-f(S-2) environment.