Engineered stone products, typically containing more than 90 percent natural quartz, which is the hardest non-precious stone, are gaining in popularity. These products are bound together by resins. These products require less maintenance than granite and marble countertops do because of their non-porous nature. Therefore, they do not need to be sealed periodically as granite does because they do not absorb liquid as granite does. Their surfaces are also more resistant to both stains and bacteria. In addition, quartz countertops are more resistant to heat than natural stone countertops. If a scratch occurs, it can easily be buffed out as well.