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Detail Slab
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Onsernone

The close-up view of each stone type shows a relatively true image of the crystalline structure and the colouring. This is suitable for grained slabs to a limited extend only. In regard to the colour matching, please take an original sample of the stone from your furniture store as a basis.

Petrography

Mainly white feldspar (albite) and transparent quartz appear in the light minerals. Because of the small size, the crystals can only be discerned under the microscope. Also included is a relatively large quantity of dark mica (biotite). However, this is not evenly distributed. Where its concentration is lower, lighter, often rather strictly in parallel arranged fine smears occur, which form a decent decor. 

Petrogenesis

Gneiss belongs to the group of the metamorphous rocks. All rocks of this group were generated, in part, under very high pressures and temperatures, which lasted for longer periods of time and more or less strongly changed the original rock in material and structure. Probably, in this case clay-sand sediments were the original rocks. Trigger for this rock transformation were the gigantic forces, which occurred with the collision of the African continent with the European continent and led to folding up a high mountain range, the present Alps.

Hardness Hard Stone
Structure Type Homogeneous Structure
Synonyms Sarizo Onsernone, Vergeletto
Group Metamorphite
Petrographic Assignment Gneiss
Age 270 million years (Carboniferous/ Permian period)
Colouring Minerals White feldspar (albite), transparent quartz, black-grey biotite
Average Hardness 6 (according to Mohs's hardness scale 1-10) / Natural stone
Deposit Vergeletto-valley in the Swiss Canton Tessin