Garavellite, FeSbBiS4, a New Mineral from the Cu-Fe Deposit of Valle del Frigido in the Apuane Alps, Northern Tuscany, Italy

F. Gregorio, P. Lattanzi, G. Tanelli and F. Vurro
Istituto di Mineralogia, Petrografia e Geochimica Università di Firenze, Via La Marmora 4, 50121 Firenze, Italy Centro CNR per la Mineralogia e Geochimica dei sedimenti
Istituto di Mineralogia e Petrografia Università di Bari, Palazzo Ateneo, 70100 Bari, Italy

Summary: Garavellite occurs in polished sections, as small aggregates, up to 200 µm across, of anhedral crystals, usually in direct contact with tetrahedrite, Sb-rich bismuthinite, chalcopyrite, and siderite. Chemical formula Fe0,80Cu0.02Sb1.13Bi0.78As0.01S4 on the basis of S = 4, or ideally FeSbBiS4.

The mineral has an orthorhombic unit cell with a = 11.439, b = 14.093, c = 3.754 Å, Z = 4; calculated density 5.64 gm/cm3. Important diffraction lines are 14.00 (m) 010, 7.08 (m) 020, 3.62 (vs) 230, 3.49 (m) 040, 3.34 (m) 320, 3.20 (vs) 121, 3.10 (m) 201, 2.98 (s) 240, 2.89 (s) 221, 2.63 (vs) 311, 2.51 (vs) 250, 2.16 (m) 421, 1.677 (m) 312. In reflected light it is grey with a brown-olive tint similar to that of tetrahedrite. Bireftectance is distinct and anisotropism is also strong, from yellowish-green to bluish grey. Vickers hardness (50 g load) 212–22 kg/mm2. Reflectance in air: 470 nm R1 = 33.5−34.7%, R2 = 40.5– 42.8%; 546 nm 32.8–34.7%, 40.2–42.0%; 589 nm 32.6– 33.7%, 39.3–41.0%; 650 nm 32.4–34.6%, 38.4–41.0%.

The mineral and name have been approved before publication by the Commission on New Minerals and Mineral Names, IMA.

Frigidite, the so-called nickel-bearing variety of tetrahedrite found at this locality, is shown to be an intergrowth of tetrahedrite and Ni-bearing minerals.

Mineralogical Magazine; March 1979 v. 43; no. 325; p. 99-102; DOI: 10.1180/minmag.1979.043.325.05
© 1979, The Mineralogical Society
Mineralogical Society (www.minersoc.org)