Granite Production choose the material from gabbro and diabase which have the character of close grain and compact structure. The stone have not the disfigurement of crack, concave, loose structure and impurity. The mineral component and physical capability are according to following :

1. Biotite : <5%
2. Modulus of elasticity : 1.3~1.5x106 Kg/cm²
3. Hardness: HS > 70 and with even hardness
4. Water absorption : ≤0.25%
5.Specific gravity : 2970~3070 Kg/m³
6.Compressive strength : 2500~2600 Kg/cm²
7.Coeff. of linear expansion :4.61x10-6

   Due to its unique features,black granite has been used extensilely in the field of measuring instruments in recent years both for traditional product (surface plates,angles,squares,etc...) as well as modern ones:three-dimensional measuring machines,physico-chemical process machine tools. suitably lapped black granite surfaces are not only extremely precise but also ideal for use in conjuntion with air bearings

DIMENSIONAL STABILITY:black granite is a natural aged material formed over millions of year and there fore siaplays great internal stability.
THERMAL STABILITY: the coefficient of linear expansion is much lower than for steel or cast iron.
HARDNESS:comparable to good-quality tempered steel.
DURABILITY:instrument last longer.
ACCURACY:the regularity of the surfaces is superiro to that obtained with traditional materials.
NON-ADHERENCE TO ACIDS,NON_MAGNETIC
ELECTRICAL INSULATOR
RESISTANCE TO OXIDATION: no corrosion,no maintenance.
COST:with state-of the-art technology prices are lower.
MAINTENANCE:Quickly and cheaply for Eventual service