Sideronatrita de Mina Santa Bárbara, Provincia de Jujuy

GALLISKI M. A. LOMNICZI DE UPTON I.

Revista de la Asociación Geológica Argentina

Instituto Salesiano de Artes Gráficas

Lugar: Buenos Aires; Año: 1992 vol. 47 p. 3 - 7

0004-4822

ABSTRACT.- Sideronatrite from Santa Barbara Mine, Jujuy Province.- The first occurrence of sideronatrite in Argentina isdescribed from the Santa Barbara sulphur Mine in Jujuy Province (23°50'40" S and 64°25' 25" W). It is associated with sulphatesof Al, Mg, Fe, Na or K, such as voltaite, metavoltine, hexahidrite, alunogen, krausite, halotriquite or goldichite in a fumarolicparagenesis that also includes sulphur, gypsum and halite. Sideronatrite appears in radiated clusters of prismatic crystals elongatedalong [001] and flattened along 1010 }, S 15 by 20011m, with (010 ), { 100} and probably { 101) as crystallographic forms. Thestrongest X-ray diffraction lines are (d in Á, 1/1 , hkl): 10.2, 100, 020; 3.05, 80, 240; 3.41, 70, 002; 2.71, 60, 170. The calculatedcell parameters are: a = 739 (3) A, be =20.59 (11) Á, c = 7.19 (2) A, V = 1095 (6) A3 and a:b:c: = 0359:1:0.349. The crystalsare pale yellow to pale orange, they have H= 2, # P {010}, vitreous luster, moderate hardness and are somewhat flexible. Underthe microscope it is transparent, bxa (+), 2V s. = 602, a = 1.509 (2), b = 1.527 (2), G = 1.585 (2), r> strong; X = b = colourless,Y = a = very pale yellow, Z = c = pale yellow. lis chemical composition by analysis is: Na 20 = 18.44, Fe2O3 = 20.6, SO3 = 42.8,1-I20 = 18.2, Cl- = 0.2, ins. = 0.2, total = 100.44. This gives the following formula: Na 226Fe024 ( (SO4)294 (OH), o2] . 3.13 H2O