Note 3 — BASIC PRINCIPLES AND “TOOLS”
Reading edition
Most of the mineral grains which make up a schist, a metamorphosed shale or sandy shale, can be seen with the naked eye, and the parallel to subparallel arrangement of platy or flaky minerals, such as the abundant mica, is the most obvious feature. In bright sunlight a schist presents a very shiny, almost silvery appearance which is caused by the reflection of sunlight from the many parallel mica plates. A phyllite has much the same mineral composition as that of a schist; however, the individual mineral grains are too small to be seen without the aid of a magnifying glass. As with the schist, a phyllite when viewed in direct sunlight, appears shiny. Quartzites are metamorphosed sandstones which have been fused into great hardness through the application of heat and pressure.