Talc in Hand Sample. Streak white. I’ve not heard of such a scale nor does it make sense. Talc, PPL Talc, Plane Polars. Talc schist; Tourmalinite; Ultramylonite (granitic) Ultramylonite (mafic) Andalusite schist The word schist is derived from the Greek word schízein meaning "to split", which is a reference to the ease with which schists can be split along the plane in which the platy minerals lie. Talc. Schist is a strongly foliated medium-grade metamorphic rock. What is Schist? It usually forms on a continental side of a convergent plate boundary where sedimentary rocks, such as shales and mudstones, have been subjected to compressive forces, heat, and chemical activity. quartzite, schist, gneiss, veins. What is Mohs Hardness Scale? The test is useful because most specimens of a given mineral are very close to the same hardness. The hardness of Schist is 3.5-4 whereas its compressive strength is Not Available. Talc is a soft mineral, measuring about 1 on the Mohs hardness scale. Schist is available in black, blue, brown, dark brown, green, grey, silver colors. This test compares the resistance of a mineral to being scratched by ten reference minerals known as the Mohs Hardness Scale (see table at left). Schist has medium to large, flat, sheet-like grains in a preferred orientation (nearby grains are roughly parallel). Rocks are made up of one or more minerals. It is defined by having more than 50% platy and elongated minerals (such as micas or talc), often finely interleaved with quartz and feldspar. The streak of a rock is the color of powder produced when it is dragged across an unweathered surface. Talc in plane polarized light. Talc is known for being the softest mineral on earth. The softest of the common minerals, it can be scratched with a fingernail. It is characterized by an abundance of platy or elongated minerals (micas, chlorite, talc, graphite, amphiboles) in a preferred orientation.Varieties of this rock type share similarities in appearance (schistosity) but may be highly variable in composition. Talc (Mg Silicate) Luster nonmetallic, pearly to greasy or dull. The hardness scale is a way to check for hardness of minerals using minerals as examples. I think you are confused. Color variations include amethyst, smoky, rose, and milky quartz. Talc. Usually pale green, also white to silver-white or gray. Talc in Thin Section Thin Section GigaPans. Talc, plane polars Talc, crossed polars Talc tremolite schist, plane polars Talc tremolite schist, crossed polars. Gypsum is harder: it can scratch talc but not calcite, which is even harder. Electronics and glassmaking. It is described as actinolite-talc schist and its source is the Catalina Schist, Santa Catalina Island, California. According to the scale, Talc is the softest: it can be scratched by all other materials. The streak of Schist is white whereas its fracture is conchoidal. Streak is the color of rock when it is crushed or powdered. One of the most important tests for identifying mineral specimens is the Mohs Hardness Test. The streak of Schist … Schist is a foliated metamorphic rock made up of plate-shaped mineral grains that are large enough to see with an unaided eye. Platy. It is number 1 on the Mohs hardness scale, and can be easily scratched by a fingernail.Talc is not commonly seen in collections, as it is usually uninteresting and fairly common, although a few deeply colored and … Some metamorphic rocks. It goes from a hardness of 1 for talc to 10 for diamond. Schist is a medium grade metamorphic rock with medium to large, flat, sheet like grains in a preferred orientation. Hardness 1. 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