General Information & Granite Selection

All Granites Are Not The Same.

Pyramid Granite & Metals Inc. produces granite products from several types of granite, depending on the customer's needs. Government tests have shown that fine-grained black granites are stronger, denser and less absorptive than other granites. For this reason precision machine bases, air-bearing surfaces and accessories are best made from black granite.

Since black granites contain no crystalline quartz and little mica, they have a very high modulus of elasticity, producing superior load-carrying capacity. Black granites have uniformly fine textures and tight porosity, characteristics which make this igneous rock extremely resistant to water absorption or warping from humidity. The superior stiffness of black granites is highly desirable for surfaces where accuracy and stability are essential.

Lighter-colored gray granite (quartz diorite) is excellent for large surface plates and machine bases subject to heavy wear, both because of its high quartz content and lower price. All the granites we use have been carefully measured to establish the modulus of elasticity, allowing us to comply with federal specifications and user requirements.

Our knowledgeable staff can assist you in choosing the best granite for your product, based on considerations of uniformity of surface, accuracy, deflection under load, type of use and price.

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