The Analysis of feldspar characteristic as ceramic material at Mount Ragas, Jepara, Central Java

Abstract

The ceramic industry in Indonesia is growing rapidly so it needs a lot of raw and mixture materials for ceramics. One of the materials needed in the manufacture of ceramics is feldspar. At Mount Ragas, located in Clering Village, Donorojo, Jepara, Central Java, there are feldspar deposits which have the potential to supply the demand of the ceramic industry. The purpose of the study was to determine the geological conditions, mineralogical composition, chemical composition and characteristic of feldspar in ceramic industry. The research methods used were geological mapping, petrographic analysis and XRF geochemical analysis. The lithology of research area consists of andesite and alluvium deposits. Andesite is composed of plagioclase (andesine), alkali feldspar, quartz, hornblende, pyroxene and opaque mineral. The chemical composition of feldspar consists of SiO2 (61.03-65.01%), Al2O3 (20.23-22.5%), K2O (5.27-5.52%), Na2O (4.65-5.1%), CaO (0.43-0.65%), Fe2O3 (0.61-2.13%), MgO (<0.01%), MnO2 (<0.01%), TiO2 (0.09-0.11%), Cr2O3 (<0.01%), LOI (1.65-1.73%). Based on SNI No. 1145-1984, no samples meet the requirements for porcelain materials, only sample SMP-05 meets the requirements for sanitary materials and samples SMP-04, SMP-05 and SMP-06 meet the requirements for pottery material. Based on the standard from PT Semarang Mineral Pembangunan, feldspar samples that meet the requirements for glass materials are SMP-04 and SMP-05 and samples that meet the requirements for ceramic materials are SMP-01, SMP-02, SMP-03 and SMP-06.