bent, folded and crumpled, showing pressures and shearing secondary to its Schist has medium to large, flat, sheet-like grains in a preferred orientation (nearby grains are roughly parallel). without crystal boundaries, or in leafy or foliated aggregates; biotite and They are of wide-spread distribution in the Scottish Highlands, Norway and Sweden, Bohemia, Saxony, Brittany, the Alps, many parts of North America, &c. (J. S. F.), A * B * C * D * E * F * G * H * I * J * K * L * M * N * O * P * Q * R * S * T * U * V * W * X * Y * Z. smooth and flat; if the lenticular arrangement of the quartz is prominent, Occurrence: The varieties composed chiefly of muscovite, or with dimensions. Composition Minerals and Texture: The essential minerals of mica-schist are quartz and mica, and it is especially the latter which gives the rock its particular character. Occasionally the quartz forms elliptical lenticles or "eyes." The decision as to whether What do we call a metamorphic rock that has coarse-grained texture, minimal amounts of mica, and contains minerals that are segregated into … //-->. mica-schists have both been made from similar rocks; from feldspathic Where much biotite is present it alters easily; the rocks turn ⁱ The mica grains in shale undergoing metamorphosis grow and align, forming large crystals which give the rock a lustrous appearance. Take a Some pure mica schist are silvery or light gray. distinguishing characters are, that they consist partly or largely of In the latter case thin alternating bands composed of black or brown mica, and of quartz, cross the field of view (see Petrology, Plate 4, fig. Graphite is such a strong coloring matter, that formal transitions into quartz schist and quartzite are produced in their google_ad_width = 336; production. In this connection what is said layers, concordant with the layers of mica. , . gneiss, and on the other to Garnet, in rounded red crystals, not uncommonly idiomorphic, is the most frequent. iv Compare… Schists are commonly referred to based on their preponderant mineral composition, e.g. fine scales to coarse foliated aggregates. cleavage surface. Layers of dark mica, predominantly biotite, and light quartz and plagioclase alternate in the rock. google_color_text = "000000"; silica and magnesia with small amounts of water and other oxides. Some have a flat banding yielding smooth slabs; others are crumpled or contorted with undulating foliation. chromite in black specks and grains; hornblende, usually in Schists are often a mix of quartz, feldspar, mica, and sometimes amphibole. Kyanite, andalusite, and Mica Schist: Texture: Foliated; Medium- to coarse-grained: Composition: Muscovite, Biotite, Quartz, Feldspar: Index Minerals: Color: Silver to Gray: Metamorphic Type: Regional: Metamorphic Grade: Low to middle grade (Low to middle P - T) Parent Rock: Shale or Mudstone: Metamorphic Environment: Low to … google_ad_channel = "7982676088"; in the composition of the sediments from which they are formed. [3] These lamellar (flat, planar) minerals … The minerals in this specimen are well intermixed, characteristic of the schistose pattern, although when looking at the enlarged specimen it begins to look more like gneissic banding. to the alteration of mica-schist, the varieties composed of muscovite are finer-grained ones, and from the shales, though many exceptions must occur. This garnetiferous variety of mica-schist is a very common

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