If you’re thinking of redoing your kitchen countertop, you’ve probably seen a lot of quartz options lately. Except you don’t want anything fake or synthetic, but rather something natural. So that begs the question: Is quartz natural stone? How do you know which variety of quartz is natural? We’ll explain below.
Quartz is the second most abundant mineral in Earth’s crust, behind feldspar. It also exists in several different varieties, usually used as jewelry and headstone materials.
Quartz is a rock, but it has an icy look about it. The ancient Greeks called quartz krustallos, whose root kruos translates to “icy cold,” believing that the rock was a form of supercooled ice.
Most varieties of quartz are colorless and transparent and are traditionally known as rock crystals.
Color differences arise from the presence of impurities in the crystal’s molecular makeup. Such changes change molecular orbit, allowing for electronic transitions in the visible color spectrum, allowing the naked eye to see regular quartz crystals in different colors.
Quartz typically comes from quarries worldwide, usually in India, Brazil, Mexico, and the US. No product is truly 100 percent quartz. After extraction, the quartz gets generally weighed to about 90 percent quartz before it gets combined with other materials, such as polyester resins and pigments.
Large amounts of pressure then compact the quartz and other materials together to create the slabs. With all materials packed so close together, it doesn’t allow liquids to seep into the slab.
Finally, the slabs are cured together in kilns, which creates a seal to truly maintain the slab’s nonporous nature. A finish completes the slab’s look.
Caches of naturally colored quartz exist all over the world.
Smoky quartz is gray, sometimes brownish-gray or black. The color arises from natural irradiation acting on the aluminum found in the crystal structure.
Milky quartz is the most common crystalline quartz. The color comes from small, trapped fluid inclusions of gas, liquid, or both when the crystal forms.
Rose quartz is pale pink or light red because of small bits of manganese, iron, or titanium. Some samples contain microscopic rutile needles that produce a small group of star-like lights in transmitted light. Crystalline rose quartz, a rare variety of rose quartz, has a color created by phosphate or aluminum traces.
Amethyst ranges from bright violet to lavender and gets its color from traces of iron.
Synthetic quartz is treated with heat or radiation to produce different colors. Quartz might also get coated with metal vapors to create a lovely sheen over the gemstone.
Sometimes it’s hard to tell the difference between natural and synthetic quartz. Previously observed in Poland, natural prasiolite is mint green, but heat treatment can create the same olive color in synthetic quartz. Citrine also occurs naturally but can be synthetic through heat-treating smoky quartz and amethyst (purple-colored quartz).
Some varieties of clear quartz receive artificial color through heat or gamma irradiation. However, how well that variety of quartz takes to the intended color depends on where the quartz gets mined.
Whether quartz is natural stone depends on what type of quartz you’re looking at. Overall, it is a naturally occurring stone but is not mined in for slabs for tabletops.