Colombian silica sands

摘要

Silice Sand Business (SSB), a Colombia-based company, has identified silica sand resources exceeding 20m. tonnes and grading 98.9 percent SiO_2 within the San Luis Valley of the Tolima State in Colombia. The silica is found within sedimentary rocks of Cretaceous to Quaternary age. The most recent deposits are alluvial in nature and consist of sandy beds intercalculated with areas of angular quartz. These deposits are irregular and are of very little thickness. Underlying these are Cretaceous grey to red shales, which are interstratified with weathered silica. Below this section are the oldest rocks in the formation, which are those of economic interest. They form part of the Guadalupe Group and are also of Cretaceous age. The deposit has an average thickness of 15 metres and is formed of a high percentage of angular quartz which is only partially weathered in the upper sections of the body. Here, the silica is characterised by brown oxidisation.