Quick Fact
On Earth, quartz is the second most abundant mineral by volume in the crust, and feldspar is the most common when considered as a single mineral group—feldspars make up roughly 50–60% of the Earth’s crust by volume.
Which two minerals are the most common on Earth?
Feldspar and quartz are the two most common minerals on Earth.
Feldspar takes the top spot as the most abundant mineral group in the crust—it makes up about 50-60% by volume. Quartz follows as the second most common mineral, accounting for roughly 10-12% of the crust. Together, they dominate the mineral landscape, which is why you’ll find them in everything from mountain rocks to beach sand. Honestly, if minerals had a popularity contest, these two would win by a landslide.
Why are feldspar and quartz so abundant?
They’re abundant because of their simple chemical structure and widespread formation conditions.
Both minerals are silicates, which means they’re built from silicon and oxygen—the two most common elements in the Earth’s crust. Feldspar forms from cooling magma, while quartz crystallizes from silica-rich fluids. Their ingredients are everywhere, and they form under conditions that have existed for billions of years. (Think of them as the basic LEGO bricks of the mineral world—easy to find, easy to assemble.)
How much of Earth’s crust do feldspar and quartz make up?
Together, they account for over two-thirds of the Earth’s crust by volume.
Feldspar alone makes up 50–60%, and quartz adds another 10–12%. That’s a combined total of roughly 60–72%—a massive chunk of the planet’s rocky shell. If you scooped up a random handful of crust, chances are good you’d be holding mostly feldspar and quartz. (And maybe a few stray pebbles.)
What types of feldspar exist?
The main types are orthoclase, plagioclase, and microcline.
These aren’t just fancy names—they represent different chemical compositions and crystal structures. Orthoclase is potassium-rich, plagioclase contains sodium or calcium, and microcline is a low-temperature form of orthoclase. All three are part of the same mineral family, though, and they often appear together in rocks like granite. You’ll rarely find them in pure form, but they’re usually mixed in with quartz and other minerals.
What’s the difference between feldspar and quartz?
Feldspar is a group of minerals with varying compositions, while quartz is a single mineral with a fixed formula.
Feldspar’s chemical formula can change—it might include potassium, sodium, or calcium, for example. Quartz, on the other hand, is always SiO₂: one silicon atom bonded to two oxygen atoms. Quartz is also harder (7 on the Mohs scale) and more resistant to weathering, which is why it ends up as sand while feldspar breaks down into clay. (You could say quartz is the tough survivor of the mineral world.)
Where do feldspar and quartz form?
Both form deep in the Earth’s crust under high-temperature conditions.
They start their lives as magma cools or as hot fluids deposit minerals in cracks. Over millions of years, erosion and tectonic forces bring them closer to the surface. Quartz often ends up in veins or geodes, while feldspar is commonly trapped in igneous rocks like granite. If you’ve ever seen a granite countertop, you’ve seen feldspar and quartz side by side—nature’s own mosaic.
What are the main uses of feldspar?
Feldspar is primarily used in ceramics, glass, enamel, and as a filler in paints.
Its low melting point makes it perfect for ceramics—it helps glaze fuse smoothly. In glassmaking, feldspar provides alumina, which strengthens the final product. You’ll also find it in enamel coatings for appliances and as a cheap, abundant filler in paints. (It’s the unsung hero of industrial materials.)
What are the main uses of quartz?
Quartz is used in glass, electronics, abrasives, and building materials.
Its clarity and durability make it ideal for glass—both the windows in your home and the screens on your phone. Quartz’s piezoelectric properties (it generates electricity when squeezed) are why it’s used in watches, radios, and even some types of sensors. You’ll also find it in sandpaper (as an abrasive) and concrete (as an aggregate). Honestly, if you’ve ever used anything made of glass or electronics, you’ve relied on quartz.
Can you find feldspar in everyday life?
Yes—it’s commonly found in granite countertops, sandstone, and some ceramics.
Look closely at a granite countertop, and you’ll see pink, white, or gray flecks—that’s feldspar. Sandstone is often made of sand-sized feldspar grains cemented together. Even some bathroom tiles and dinnerware contain ground-up feldspar. It’s not as flashy as quartz, but it’s everywhere if you know where to look. (Try shining a flashlight through a piece of granite at night—those little sparkles? Probably feldspar.)
Can you find quartz in everyday life?
Absolutely—it’s in sand, geodes, and even some jewelry.
Quartz is what most sand is made of—those tiny, translucent grains you see at the beach. If you’ve ever cracked open a geode, you’ve likely found clear or purple quartz crystals inside. And if you’ve worn a piece of jewelry with a shiny, faceted stone, there’s a good chance it was quartz (or a quartz variety like amethyst or citrine). Even your phone’s screen probably contains a thin layer of quartz. (It’s the mineral that just won’t quit.)
How can you tell feldspar and quartz apart?
Try scratching glass—quartz will scratch it, but feldspar won’t.
Quartz is harder (7 on the Mohs scale), so it can scratch glass, steel, and even your fingernail in a pinch. Feldspar, at 6 on the scale, is softer and won’t leave a mark. Color can help too—feldspar often appears pink, white, or gray, while quartz is usually clear, white, or milky. (Though both can come in a rainbow of colors thanks to impurities.) Another trick? Feldspar often has flat, shiny surfaces where it’s broken, while quartz tends to fracture in curved patterns.
Where are the best places to find feldspar and quartz?
Look in granite formations, pegmatite veins, and riverbeds.
Granite outcrops—like those in Yosemite or the Sierra Nevada—are packed with both minerals. Pegmatite veins, which are like mineral-rich cracks in rock, often contain giant quartz crystals and well-formed feldspar. Riverbeds and beaches are great for small quartz grains, while feldspar is easier to spot in coarse-grained rocks. If you’re serious about collecting, check out pegmatite mines in places like the Black Hills (South Dakota), the Alps, or Brazil. (Just don’t forget your rock hammer—and a permit if you’re on public land.)
Are feldspar and quartz valuable?
They’re valuable industrially, but not typically as gemstones (except for varieties like amethyst).
As raw materials, they’re incredibly valuable—feldspar is a key ingredient in ceramics and glass, and quartz is essential for electronics and construction. As gemstones, though, only certain varieties (like amethyst or rose quartz) fetch high prices. Most feldspar and clear quartz are too common to be worth much as jewelry. That said, a huge, flawless quartz crystal can still sell for thousands—especially if it’s from a famous locality. (Rarity matters, even for common minerals.)
How do feldspar and quartz weather differently?
Quartz is highly resistant to weathering, while feldspar breaks down into clay.
Quartz’s tight crystal structure makes it nearly indestructible—it just gets smaller and rounder over time, eventually becoming sand. Feldspar, though, reacts with water and acids (like rainwater) to form clay minerals. This process is why fertile soil often contains clay: it’s basically weathered feldspar. (So next time you hold a handful of soil, thank feldspar for keeping plants happy.)
Can feldspar or quartz be used in technology?
Yes—quartz is widely used in electronics, while feldspar has niche applications.
Quartz’s piezoelectric properties make it perfect for oscillators in watches, radios, and even some medical devices. It vibrates at a precise frequency when electricity is applied, keeping time or stabilizing signals. Feldspar isn’t as flashy, but it’s used in some ceramics for electronics and as a flux in soldering. (Think of it as the behind-the-scenes player in tech.)
What’s the largest quartz crystal ever found?
As of 2026, the largest quartz crystal ever recorded reached over 6 meters in length.
This giant was discovered in a mine in Kazakhstan. Most quartz crystals are tiny, but this one was massive—taller than two tall adults stacked on each other. While such giants are rare, quartz crystals of all sizes are surprisingly common. You might not find a 6-meter monster in your backyard, but a little digging could turn up a palm-sized treasure. (Just don’t expect it to be worth millions—unless it’s a rare variety like ametrine.)
How can I start collecting feldspar or quartz?
Visit rock and mineral shows, commercial mines, or public collecting sites (with permits).
Start small: check local gem and mineral shops for tumbled stones or raw specimens. Rock and mineral shows happen year-round in the U.S. and Europe—these are great places to see (and buy) polished quartz and feldspar up close. For a hands-on experience, visit a commercial mine or a fee-collecting site, where you can dig for your own specimens. (Just remember: always follow local laws about collecting on public land. When in doubt, ask for permission—or stick to buying from dealers.) If you’re lucky, you might even find a dealer who cuts and polishes quartz on-site—it’s a dazzling way to see the transformation from rock to gem.
Why do feldspar and quartz matter to geology?
They’re fundamental to understanding Earth’s crust and its processes.
Feldspar and quartz make up the bulk of the continental crust, so studying them helps geologists piece together the history of mountain formation, erosion, and even plate tectonics. Their weathering patterns shape soil composition, which affects ecosystems and agriculture. And their presence in rocks tells us about the conditions under which those rocks formed. (In other words, they’re the bread and butter of geological detective work.) Without them, Earth’s crust would look entirely different—and so would the landscapes we live on.
