Learn About Natural Stone
Plain-English guides written for homeowners — not contractors. Built on ASTM dimension stone standards and decades of field experience.
Understand stone before you buy it
Natural stone is one of the most consequential — and most misunderstood — choices in a renovation. Two slabs that look nearly identical in a showroom can behave completely differently in your kitchen: one shrugs off lemon juice and hot pans, the other etches the first time someone sets down a glass of wine.
The difference comes down to geology, not marketing names. This hub explains what actually matters — stone families and how they behave, the tests pros use to tell them apart, the standards that define quality, and the vocabulary you will hear from fabricators and suppliers. Read these before you commit, and you will ask better questions and avoid expensive surprises.
Quartzite vs Marble: How to Tell the Difference
A 5-minute test cuts through the labeling confusion. Find out whether the slab in front of you is real quartzite — or marble in disguise.
6 min read
ASTM Dimension Stone Standards Explained
What the ASTM number on a stone spec sheet actually means. Plain-English guide to C503, C615, C616, and the rest — and which numbers matter for which use.
8 min read
How to Identify a Stone Yourself
The glass scratch test. The acid drop test. The powdered rock test. The tools fit in a small kit, and the answers take minutes — not weeks of guesswork.
7 min read
Stone types, at a glance
Every natural stone belongs to a family defined by how it formed. The family — not the trade name — predicts how a stone resists acid, scratches, heat, and water. Here are the six you will encounter most. Tap any type to browse every stone of that kind in our catalog.
Marble
Calcite-based · Mohs 3–5 · acid-sensitive
Prized for its soft veining and timeless look. Because it is calcite-based, marble etches when it meets acids — lemon, vinegar, wine, many cleaners — leaving dull marks that are not stains. Best for vanities, fireplaces, walls, and lower-traffic surfaces, or for owners who embrace a lived-in patina.
Granite
Quartz & feldspar · Mohs 6–7 · low-maintenance
An igneous workhorse: hard, heat-resistant, and largely acid-proof. With periodic sealing it handles the busiest kitchens with ease. Ranges from uniform speckles to dramatic movement, so there is a granite for nearly every aesthetic.
Quartzite
Siliceous · Mohs 7 · acid-resistant
Metamorphosed sandstone — genuinely hard and acid-resistant, which makes true quartzite a favorite for kitchens that want a marble look without the fragility. The catch: many slabs sold as quartzite are actually marble or dolomite. Always verify before you buy.
Travertine
Calcite-based · porous · acid-sensitive
A sedimentary stone formed around mineral springs, full of natural voids that are usually filled at the factory. Warm and classic for floors, exteriors, and bathrooms. Like marble it is acid-sensitive and benefits from sealing.
Limestone
Calcite-based · soft · porous
Understated and matte, limestone reads as calm and architectural. It is soft, porous, and acid-sensitive, so it shines on walls, floors, and exteriors more than on hardworking counters. Sealing is essential.
Onyx
Calcite-based · translucent · delicate
A showpiece stone, often translucent enough to backlight. It is soft and acid-sensitive — reserved for accent walls, bar fronts, and feature pieces rather than everyday surfaces. Handle as a finish, not a tool.
Our catalog also covers dolomite, soapstone, slate, sandstone, and serpentine. Browse the full library to compare any of them side by side. Browse all stones →
Frequently asked questions
What is the real difference between marble and quartzite?+
Quartzite is siliceous and hard (Mohs ~7), so it resists acids and scratches. Marble is calcite-based and softer (Mohs 3–5), so it etches from everyday acids like citrus and wine. They can look almost identical, which is why slabs are so often mislabeled — see our full quartzite vs. marble guide.
Does all natural stone need to be sealed?+
Most porous stones benefit from an impregnating sealer, but how often depends on the stone's water absorption, not the type alone. Dense quartzites may need it rarely; porous marble, travertine, and limestone need it regularly. Each stone page lists a sealer recommendation.
What does it mean when stone “etches”?+
Etching is a dull, often lighter mark left when acid reacts with calcite — it is physical surface damage, not a stain sitting on top. It affects marble, limestone, travertine, and onyx. A honed finish hides etching far better than a polished one.
Is granite or quartzite better for a kitchen?+
Both are excellent: hard, heat-tolerant, and acid-resistant. The choice usually comes down to look and budget rather than performance. Granite offers more uniform options; quartzite tends toward marble-like movement at a higher price.
How can I tell what stone I actually have?+
A few simple field tests — a hardness scratch, an acid drop, a water-absorption check — narrow it down quickly. Our diagnostic tests guide walks through each one, and our photo identifier can suggest matches from a picture.
What is ASTM and why should I care?+
ASTM International publishes the technical standards that define acceptable absorption, density, and strength for each stone category. When a supplier cites an ASTM spec, it is a verifiable quality benchmark — our ASTM standards guide explains what each number means.
Are quartzite and quartz the same thing?+
No — and the names cause endless confusion. Quartzite is 100% natural stone quarried from the earth. Quartz countertops are engineered: ground minerals bound with resin in a factory. They look, cost, and behave differently.
What is the difference between honed and polished?+
Both describe a surface finish. Polished is glossy and reflective, deepening color and veining. Honed is matte and smooth, with a softer, more contemporary look that also disguises etching and scratches better — a practical choice for acid-sensitive stones.
Glossary of stone terms
The words you will hear from fabricators, suppliers, and installers — defined plainly.
- Etching
- Dull marks caused by acid chemically reacting with calcite-based stone. It is surface damage, not a stain, and cannot be wiped away.
- Honed
- A smooth, matte finish achieved by stopping short of a full polish. Hides etching and scratches better than polished.
- Polished
- A glossy, reflective finish that intensifies color and veining. The most common showroom finish.
- Water absorption
- The percentage of water a stone takes in — a key porosity measure that drives sealing needs and stain risk.
- Calcareous
- Calcite-based stone (marble, limestone, travertine, onyx). Reactive to acids and prone to etching.
- Siliceous
- Quartz-based stone (granite, quartzite, sandstone). Generally hard and acid-resistant.
- Resin-fill
- Factory-applied resin that fills natural pits and fissures, common on travertine and softer marbles, for a smoother slab.
- Mohs hardness
- A 1–10 scratch-hardness scale. Marble sits near 3–5; granite and quartzite near 6–7.
- Impregnating sealer
- A penetrating treatment that lines a stone's pores to slow stain absorption. It does not prevent etching.
- AntiEtch®
- A professional treatment that gives acid-sensitive stone a durable, etch-resistant surface — letting marble live in a kitchen.
- ASTM specification
- An industry standard (e.g. ASTM C503 for marble) defining acceptable physical properties for a stone category.
- Slab
- A large, finished sheet of stone cut from a block, from which countertops and surfaces are fabricated.
Put it into practice
Browse technical data on every stone in our library, or upload a photo to identify the stone in front of you.