Ornamental stones from the Cunene anorthosite complex, Angola: the “Negro”lithotype anorthosite and the red granites

Abstract

[EN] The anorthosites (“black granites”) and associated red granites occurring in selected areas of the Cunene Anorthosite Complex (SW Angola) were assessed regarding its ornamental potential. The results of the field survey in an area of the Huíla province, analysis and tests carried out on collected samples reveal that anorthosites are high quality ornamental stones for indoor or outdoor use, namely for pavement, cladding and lining. The exploited anorthosites occur in varied lithotypes, in terms of texture, mineralogy and color, which is generally the most differentiating factor. One main trade lithotype, the “Negro Angola” has its central extraction area in the Tchiquatite quarrying site, due to the finer granularity and greater homogeneity of the stone when compared to other sites in the region. The red granites were studied in two areas of the complex revealing ornamental quality but the potencial is low due to alteration, intense fracturing, and frequent flaws.