MINERALOGÍA DE THOMSONITA. JUNíN DE LOS ANDES, NEUQUéN

VATTUONE, M.E.; CROSTA, S.; BERBEGLIA, Y.; MARTÍNEZ DOPICO, C.I.; GALLEGOS, E.

Ciudad de Buenos Aires

Congreso; MINMET- VIII Congreso de Mineralog¨ªa y Metalogenia; 2006

Asociación Mineralógica Argentina; Universidad de Buenos Aires

An assemblage of thomsonite and natrolite has been found in tertiary amygdaloid basalts of Jun¨ªn de los Andes, Neuqu¨¦n. The thomsonite crystals appear in an intergrowth with natrolite. The physical and optical properties of this thomsonite are: radiated acicular crystals; lenght along c axis, with {100}, {010} and {h0l} forms; straight extintion; 2V¦Ã=45¡ã and weak dispersion r>v ; the orientation is: ¦Á, ¦Ã, ¦Â ¡Ô a,b,c. The XRD shows that a0=13,027, ,b0=13,064 and c0=13,178; Tsi=0.60 and Si/Al=1,48. These parameters are in accord with the ordered variety of thomsonite formed with natrolite in alkaline environment at low temperatures. ¦Ã=45¡ã and weak dispersion r>v ; the orientation is: ¦Á, ¦Ã, ¦Â ¡Ô a,b,c. The XRD shows that a0=13,027, ,b0=13,064 and c0=13,178; Tsi=0.60 and Si/Al=1,48. These parameters are in accord with the ordered variety of thomsonite formed with natrolite in alkaline environment at low temperatures.