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Synonyms: Onsernone Gneis, Onsernone-Gneis, Onsernone-Granit, Onsernonegranit, Onsornone, Sarizzo Onsernone, Vergeletto
Location: Onsernone granite is quarried 6 km behind Vergeletto, Val Vergeletto, Ticino, European Alps , Switzerland.
Description: Onsernone granite is a fissionable, fine-grained, dark to medium grey gneiss (paragneiss) of the Carboniferous/Permian period. 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. Ideal for both interior and exterior use, Onsernone granite should be frost free and polish constant.
Technical and Physical Characteristics:
CCompression tensile strength: 1720 kg/cm2
Tensile strength after freeze-thaw cycles: 1664 kg/cm2
Unitary modulus of bending tensile strength: 139 kg/cm2
Heat expansion coefficient: 0.0050 mm/m°C
Water imbibition coefficient: 0.003200
Impact strength: 86 cm
Mass by unit of volume: 2661 kg/m3
Gneiss: A high grade metamorphic rock. This means that gneiss has been subjected to more heat and pressure than schist. Gneiss is coarser than schist and has distinct banding. This banding has alternating layers that are composed of different minerals. The minerals that compose gneiss are the same as granite. Feldspar is the most important mineral that makes up gneiss along with mica and quartz. Gneiss can be formed from a sedimentary rock such as sandstone or shale, or it can be formed from the metamorphism of the igneouse rock grantite. Gneiss can be used by man as paving and building stone.