1. Natural or Not?
Both countertop materials are overwhelmingly made of natural product, but one comes out slightly ahead:
Granite: 100% natural. Slab granite counters are literally sliced from quarries, cut to size, and honed down until they are smooth.
Quartz: 93% natural quartz aggregates are mixed with the remaining 7% of color pigments and polymer resins. The resins bind the particles together.
2. Radon
Radon is a radioactive gas that has been linked to lung cancer. Radon can be found in granite and quartz. Radon in countertops is a contentious issue. I argue that homeowners have little to fear about radon in counters, as it appears to have been an overwrought media scare that began around 2008.
Granite: The magazine Consumer Reports indicates that a scientist found "almost no radon" coming from the granite.
Quartz: The same publication found "very little" radon in engineered stones.
3. Maintenance
Stone, whether natural or engineered, seems like it should be maintenance-free. Not so. Both materials require maintenance, with granite requiring more than quartz:
Quartz: Quartz does not need initial or continued sealing.
Granite: Granite needs to be sealed upon installation, and then again on a regular basis.
4. Durability
Quartz: Engineered stone has the flaws engineered out. You will not find invisible striations just waiting to crack open some day, as you will find with slab granite. Due to the presence of the resins, quartz counters are less prone to staining.
Granite: Natural slab granite, for all its beauty, has flaws and imperfections that homeowners either love, accept, or hate. Granite stains if subjected to red wine.