Slate is a a metamorphic stone formed by intense heat and pressure. While the stone can withstand even higher temperatures than many metals can, it may also shatter or fall apart, depending upon the thickness, the variety of slate and the conditions under which it is heated.
Slate as Construction Material
Slate withstands temperature extremes, surviving both freezes and intense summer sun, making it a durable option for a hearth, as a roofing material or even as flooring. The type of slate used for roofing and hearths is chosen for its ability to withstand temperature changes. Slate is found in various places around the globe, but some versions are more stable against temperature changes than others. Slate is an excellent backsplash material since it resists heat and burning. It is also used for countertops, flooring and sometimes as an outdoor surface for walkways or driveways.
Slate and Heat
Slate itself is fireproof, but thin pieces of slate may shatter or fall apart if placed in a fire or hot oven while the stone is cool. The amount of heat a particular piece of slate can withstand really depends upon the stone itself. Thick, quality pieces of slate may withstand the intense heat of a barbecue grill even better than the metal or plastics used on other parts of the grill. Slate slabs designed to be used as countertops or hearths are chosen for their ability to withstand just about any level of heat they may face under normal fireplace or kitchen conditions. Most slate is stain-resistant as well, so a hot pot will not leave behind a burn mark on a slate hearth, countertop or table.
Slate and Foods
Some manufacturers offer slate plates designed specifically for kitchen-related use. While these plates can be used to serve hot foods or even placed in a freezer to keep desserts and drink glasses cold, many such plates are not oven-proof and should not be used in either an oven or microwave. Other companies manufacture slate pieces designed to be used as cookware. In either case, read the manufacturer's recommendations for the slate product to determine whether the product is meant to withstand high temperatures.
Do not use slate tile in an oven or atop the stove as it may shatter. Slate slabs used for cooking are generally much thicker than slate found in a home improvement store and less likely to shatter easily.
Kathy Adams is an award-winning writer. She is an avid DIYer that is equally at home repurposing random objects into new, useful creations as she is at supporting community gardening efforts and writing about healthy alternatives to household chemicals. She's written numerous DIY articles for paint and decor companies, as well as for Black + Decker, Hunker, SFGate, Landlordology and others.