The mineralogical composition of Prima Porphyry is made up of quartz, sanidino, plagioclase, subordinante biotite and vitreous material. It is a magmatic rock, one of the stongest and therefore very suitable for combatting the inevitable ageing process due to the chemical and physical actins of atmospheric agents and to pollutin. Porphyry is also a material which is very resistent to the attack of chemical agents even those containing lubricating oils. The strength and roughness of its surface are essential characteristics in this sense.

Following the chemical composition:

Silicon oxide: 73,68%

Aluminium oxide: 12,05%

Titanium dioxite: 0,05%

Iron oxide: 2,62%

Calcium oxide: 0,63%

Magnesium oxide: 0,72%

Potassium oxide: 5,77%

Sodium oxide: 2,06%

Loss on heating: 1,95%

– Compressive strength UNI19724/4:
resistance to monoaxial compression, average value: 221,5 MPa

– Resistance to deformation UNI9724/5:

breaking strain under indirect traction through flexion, average value: 22,5 MPa

– Coefficient of linear thermal expansion:

coefficient of linear thermal expansion, average value: 5,55 10 -6/* C

– Coefficient of normal elasticity:

elasticity tangent modulus Et: 66.180MPa; elasticity secant modulus Es: 59.360 MPa

– Impact test:

impact test, minimum fall height, average value: 620mm

– Knoop micro hardness: UNI 9726/6:

knoop micro hardness test, average value: 5.416 MPa

– Coefficient of absorption

coefficient of absortion, average value: 6,53%o

– Resistance to freeze

monoaxial compression after freezing, average value: 202,6 MPa

– Resistance to abrasion:

resistance to abrasion, relative value with reference to the S. Fedelino granite: coefficient 1,51

Source: Il manuale del Porfido, Paolo Tomio Fiorino Filippi, Publistampa, Pergine Valsugana (TN), 1996