Ponta Grossa and Castro zones in Paraná talc district, Brazil, ore properties and mineral industry
Resumo
Talc deposits of Paraná district occur as layers, lenses, veins and irregular bodies. The country
rocks are dolomite marbles of the late proterozoic Itaiacoca Group. The talc ores are generally in
situ, formed by metamorphic and hydrothermal processes, but there are some deposits that present
concentrations of alloctone materials. These materials are partially remobilized by carstic dissolution
and/or by colluvionar transport.
Talc ores differ due their chemical composition, morphology, associated minerals, whiteness
and some other properties. The talc minerals in the district of Paraná can be unctuous and not
unctuous, platy and powdery, sparry and micro-crystalline and some form massive and disseminated
ore deposits.
The Southern zone or Ponta Grossa zone exhibits a talc ore more lamellar, platy, unctuous,
softness and more varied associated minerals than the ore situated in Northern zone or Castro
zone in which the talc is more powder in natural way.
There is one deposit in the São José mine that belongs to the Ponta Grossa zone, that is an
exception comparing with the other deposits in terms of its presented characteristics.
The parameters that govern the specific nature of each commercial talc grade as well as its
use in industrial applications including the polypropylene manufacturing are discussed in this
paper.
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PDFDOI: http://dx.doi.org/10.5380/geo.v50i0.4150