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Grigio Beola

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

In the Domodossola area several varieties of fine-grain to fine-scales, well separable plate gneiss is found, which are known under the collective term "Beola". The most common type is Grigio Beola. This is a light grey rock oriented in parallel layers. The average grain size is 1 to 2 mm, the mineral content is made up of light grey feldspar, grey to milky-grey quartz, layers of fine, black biotite scales and small, silvery muscovite leaves. Muscovite (light mica) appears sparkling and nest-like in the polished surface. This gives the material its decorative shine, but leads to matt locations and craters due to the low hardness in the polish. The significant pearl string-like marking of this stone type is generated by cutting the raw blocks. 

Petrogenesis

Clay and sand containing sediments were the base material for the generation of para-gneiss. Initially, strongly slate-type mica rocks were generated due to high pressures and temperatures, as biotite and muscovite can especially easy be forced to crystallise. With further rising temperatures and higher pressure in the zone of the residual silicate, feldspars are generated and residual silicon leads to generating quartz crystals. Overall, a granite chemism exists (feldspar, quartz and mica); however, with differing mass ratios of the individual minerals.

Hardness Hard Stone
Structure Type Homogeneous Structure
Synonyms Beola Grigia Crevoladossola
Group Metamorphite
Petrographic Assignment Gneiss-Para-gneiss
Age 280 million years (Palaeozoic period)
Colouring Minerals Light-grey feldspar, grey quartz, black biotite, silvery muscovite
Average Hardness 5 (according to Mohs's hardness scale 1-10) / Natural stone
Deposit Italy / in the province Novara, near Domodossola