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The Unique Types of Natural Stone

by Daniel Morrell

Posted on January 01, 1970 12:00:00 AM

Types of Natural Stone

Hewn from the earth, cut with diamond saws, polished like glass, and shipped around the world, stone makes the most cosmopolitan of counters. It exists everywhere in the world, yet nowhere is it the same. Even from the same quarry, no two pieces are identical.

Stone is extremely dense, yet also porous; to prevent stains it must be sealed. Its very permanence makes it difficult to work and shape, but technological advances have made it possible to cut and polish stone near quarries around the world, a money-saving development that enables unusable pieces to be discovered before they are shipped abroad.

Granite, the most popular stone for counters, is an extremely hard rock formed by volcanic activity. Its shimmering beauty lies in the crystals of quartz, mica, and feldspar trapped within. So-called consistent granite has the same pattern throughout. Variegated granite has veins that vary from piece to piece, which add character but also make it difficult to match sections. Granite is very porous and should be treated with a penetrating sealer every six months to prevent stains.

Soapstone and slate are much softer than granite but also less porous. Slate was formed from clay on ancient sea beds and generally has a solid gray, black, or green hue. Soapstone, which is composed primarily of the mineral talc, has a similar color but often contains light striations of quartz. Both stones scratch and chip easily, especially on the edges; the marks can be sanded out or left to add character. Combined with a sink of the same material, slate or soapstone counters can create a classic farmhouse look or a sleek, refined look. It's not generally necessary to seal these stones, but a periodic application of mineral oil will make them glow.

Marble and limestone are warm and soft but less practical for kitchens because food acids stain them readily. Still, many homeowners don't mind stains that add a patina of age. And marble is a classic surface for rolling out pastry; serious bakers often include a section of marble countertop in their kitchens for this purpose. Marble is generally polished like granite; limestone is often honed to a matte finish.