Silver Cloud Granite
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Synonyms: Silver Cloude, Silver Clouds, Silver-Clowd
Location: Silver Cloud granite is quarried near Lithonia, Atlanta, Georgia, U.S.A. There is only one quarry of Silver Cloud granite, the veining is a marbling of grey and white and a small sample is not representative of the whole block or slabs.
Description: Silver Cloud granite is a fine-grained, grey to white-grey gneiss (paragneiss) of the Precambrian period with cloudy decoration, partly with pyrite and hematite. This stone internationally may be nominated as a granite but in the area of application of the European Standard this stone must be nominated as a gneiss.
The veining and colour varies considerably and a small sample of Silver Cloud granite may not be representative of the whole slab therefore swatch samples must be approved for large projects to ensure that the blocks are all extracted from the same quarry face for matching purposes. Ideal for both interior and exterior use, Silver Cloud granite is frost free and polish constant.
Mineral Composition: Orthoclase: 62%, Quartz: 27%, Hornblende: 5%, Biotite: 3%, Plagioclase: 2%, Mafite: 1%.
Technical and Physical Characteristics:
Compression tensile strength: 2080 kg/cm2
Tensile strength after freeze-thaw cycles: 1990 kg/cm2
Unitary modulus of bending tensile strength: 132 kg/cm2
Heat expansion coefficient: 0,0065 mm/m°C
Water imbibition coefficient: 0,004000
Mass by unit of volume: 2620 kg/m3
Gneiss: A common and widely distributed type of rock formed by high-grade regional metamorphic processes from pre-existing formations that were originally either igneous or sedimentary rocks. Gneissic rocks are usually medium to coarse-foliated and largely recrystallized but do not carry large quantities of micas, chlorite or other platy minerals. Gneisses that are metamorphosed igneous rocks or their equivalent are termed granite gneisses, diorite gneisses, etc.