Characteristics of the Rocks from the Corumbataí Formation Used In the Floor Tiles Industry.

Abstract

The rocks from Corumbataí Formation, successfully used by the floor tiles industries of the Ceramic Cluster of Santa Gertrudes (SP, Brazil). This cluster is located in the region of the cities of Santa Gertrudes, Rio Claro, Cordeirópolis, Limeira and Araras. Geologically, the rocks may be classified into five ceramic lithofacies, as follows: massive, laminated, intercalated I, intercalated II and altered. Chemically, they are considered as clays with medium amount of fluxing agents, and their composition of Na2O+K2O ranges from 2.9% in the altered lithofacies up to 4.31% in the intercalated I lithofacies .The main clay minerals are illite and kaolinite (both always present), but montmorillonite often occurs in the intercalated I and II, and in the laminated lithofacies. The other main minerals are quartz, albite-type feldspar and calcite. Based on the ceramic characterization the lithofacies are classified, according to the Floor Tiles Classification, within the group BIIb (BII stands for mechanical resistance ranging from 180 to 300 Kgf/cm2, and b stands for water absorption ranging from 6 to 10 %), except for some intercalated I and II and altered lithofacies samples, which presented water absorption values above 10%.