CICTERRA   20351
CENTRO DE INVESTIGACIONES EN CIENCIAS DE LA TIERRA
Unidad Ejecutora - UE
congresos y reuniones científicas
Título:
Thénardita y mirabilita en precipitados químicos litorales de la Laguna Mar Chiquita, Córdoba (Argentina)
Autor/es:
BIGLIA, HÉCTOR O.; COLOMBO, FERNANDO; PIOVANO, EDUARDO; CÓRDOBA, FRANCISCO
Lugar:
San Juan
Reunión:
Congreso; XI Congreso de Mineralogía y Metalogenia; 2013
Institución organizadora:
Asociación Mineralógica Argentina y Universidad Nacional de SanJuan
Resumen:
Thénardite and
mirabilite occur in a salt mud flat (30°56'20.43"S- 62°52'56.76"W)
related to the Mar Chiquita hypersaline lake, the largest of its class in South
America. Thénardite, NaSO4, occurs
as crusts of euhedral colorless crystals reaching 2 mm, showing the forms {111}
(dominant) and {010}, {101} and {011} (subordinate). Unit-cell dimensions
refined from X-ray powder diffraction (XRPD) data are: a = 5.8631(4), b =
12.3126(7), c = 9.8223(7) Å, V = 709.07(8) Å3. The X-ray diagram shows an excellent match with the
PDF file 1-70-1541. EDS spectra show only Na, O and S, with an Na:S ratio close
to unity. Mirabilite was identified by XRPD, with a reasonable match with the
PDF file 1-74-0937. Both minerals are associated to halite.
The origin of
these species is related to an influx of salty water from the lake to the
freatic
level, during the dry season (Winter and early
Spring).