Natural Stone 101: Types of Natural Stone Tile Explained
Natural stone is rock, quarried in blocks and cut to size. Nothing is printed on it and nothing is fired in a kiln. Which rock it is decides almost everything else: how it looks, where it can go, and how you look after it.
That is why no two pieces match, and why stone is still found in buildings meant to last. Travertine quarried near Tivoli went into the Colosseum more than 1,900 years ago. This guide covers the nine stones you are most likely to meet, the one piece of chemistry worth knowing, and how to match a stone to a room.
From quarry to tile. Stone leaves the quarry as large blocks. The blocks are sawn into slabs, and the slabs are cut and finished into tile, pavers, coping, moldings, and mosaics.
No two blocks are alike, so stone is sold by lot. Tile from one lot is consistent with itself and may differ from the next, which is why a project should be ordered in one go.
How stone forms: three families
Geologists group rock by how it formed. The family is a first clue to how a stone will look.
Sedimentary
Built up in layers and compacted into rock: shell and coral debris on a sea floor, minerals left behind by spring water, or grains of sand. Often shows bedding, fossils or pores.
Limestone, travertine, sandstone
Metamorphic
Existing rock changed by heat and pressure. Limestone recrystallizes into marble, quartz-rich sandstone into quartzite, and shale into slate.
Marble, quartzite, slate
Igneous
Molten rock that has cooled. Slowly, below ground, it grows the visible crystals of granite. Quickly, as lava at the surface, it becomes fine-grained basalt.
Granite, basalt
The one distinction that matters most
For daily life, the more useful split is not family but chemistry: what the stone is made of.
Calcite stones
Marble, limestone, travertine, onyx
Made mostly of calcium carbonate, which reacts with acids. Lemon juice, vinegar, wine and many bathroom cleaners leave dull marks called etching.
They are softer and easier to shape, which suits mosaics and moldings. Clean them with a neutral cleaner.
Silicate stones
Granite, quartzite, basalt, slate
Made mostly of silicate minerals such as quartz, feldspar and mica. They are generally resistant to the acids found in a kitchen.
Acidic cleaners are still not recommended, and these stones still benefit from sealing.
Where the minerals sit on the Mohs hardness scale
The scale ranks minerals by what scratches what, and its steps are not even, so read it as an order rather than a measurement. It still explains a lot. Sand is mostly quartz, so grit carried in on shoes is harder than a marble or limestone floor and will dull it over time. A doormat does real work.
Two caveats. Slate resists acids like the other silicate stones, but it is made of soft clay and mica minerals, so it scratches more easily than granite. Basalt is a silicate stone too and does not etch the way marble does, but acids can lighten or dull a dark honed surface, so keep it on neutral cleaners as well.
Neither group is better. Calcite stones are chosen for their color, veining, and softness of tone, and silicate stones for hard use. Knowing which one you have tells you how to look after it.
Natural stone compared
| Stone | Family | Made mostly of | The look | Acids |
|---|---|---|---|---|
| Marble | Metamorphic | Calcite | Veined, takes a high polish | Etches |
| Travertine | Sedimentary | Calcite | Warm, banded, naturally pitted | Etches |
| Limestone | Sedimentary | Calcite | Soft, even, matte | Etches |
| Onyx | Sedimentary | Calcite | Banded, lets light through | Etches |
| Basalt | Igneous | Plagioclase, pyroxene | Even gray to near-black | Varies |
| Granite | Igneous | Quartz, feldspar | Speckled, crystalline | Resists |
| Quartzite | Metamorphic | Quartz | Glassy, sugary grain | Resists |
| Slate | Metamorphic | Clay minerals, mica | Layered, cleft face | Resists |
| Sandstone | Sedimentary | Quartz grains | Warm, sandy-grained | Varies |
"Resists" means generally resistant to household acids, not immune to every chemical. Individual stones vary, so test a sample if it matters.
The stones, one by one
The first five make up most of our natural stone catalog. The rest are worth knowing, and each entry says what we carry.
Metamorphic · Calcite
Marble
Marble is limestone recrystallized by heat and pressure into a mass of interlocking calcite crystals. Pure limestone gives white marble. Impurities such as clay minerals and iron oxides give the grays, pinks, yellows and blacks. It takes a high polish, and it is the stone most people picture in a classic bathroom.
Sedimentary · Calcite
Travertine
Travertine is a variety of limestone deposited by mineral-rich spring water. It builds up in bands and keeps small natural voids, which give it its open, pitted character. Colors run from ivory and cream through gold, noce and silver.
Sedimentary · Calcite
Limestone
Most limestone forms on sea floors from accumulated shell, coral and other marine debris, and it sometimes shows them as fossils. It is quieter than marble: even color, usually a matte finish, and very little veining.
Sedimentary · Banded calcite
Onyx
The onyx sold as tile is banded calcite, deposited layer by layer by water in caves and around springs. Gemstone onyx is a different material, a banded form of chalcedony. Thin pieces of onyx tile let light through, which is why it is so often backlit.
Igneous · Plagioclase and pyroxene
Basalt
Basalt is lava that cooled at the surface: fine-grained and usually dark gray to black. It underlies more of the Earth's surface than any other rock, most of it beneath the oceans. Its even color suits clean, modern rooms.
Igneous · Quartz and feldspar
Granite
Granite forms when magma cools slowly below the surface, giving its crystals time to grow large enough to see. It is made mainly of quartz and feldspar, both hard minerals. In the trade the name also covers other hard, crystalline rocks such as gabbro, which is why a granite can be solid black as well as speckled.
Metamorphic · Quartz
Quartzite
Quartzite is quartz-rich sandstone recrystallized into interlocking quartz. At about 7 on the Mohs scale it is among the hardest stones used in building, and it stands up to abrasion better than marble.
Metamorphic · Clay minerals and mica
Slate
Slate is shale or mudstone changed by low-grade heat and pressure. Its flat minerals line up in parallel, so it splits into thin sheets with a natural cleft face. Most slate is gray, with greens, reds, purples, blacks and browns set by its iron and organic content.
Sedimentary · Mostly quartz grains
Sandstone
Sandstone is exactly what it sounds like: sand-size grains, usually quartz, held together by a natural cement. It has a grained texture and earthy color, and it has long been used for paving and walls.
Deciding between the big three? Read Marble vs Limestone vs Travertine.
Every stone has a place where it is the best possible choice. The skill is in matching the stone to the job.
The finish changes how a stone behaves
The same stone can be glossy, matte or rough depending on how its surface is worked. The finish affects grip, upkeep and where the tile can go.
Polished
Ground to a reflective gloss that shows color and veining at their deepest. Slippery when wet, and etching shows most clearly on it.
Walls, formal rooms
Honed
Smooth and matte. With less reflection, etching and everyday wear tend to be less obvious.
Most interior floors, showers
Tumbled
Edges and face softened for an aged look with more texture underfoot.
Travertine floors, pavers, backsplashes
Brushed
Worked with abrasive brushes to a soft, lightly textured surface.
Limestone and travertine floors
Flamed
Roughened with heat to give a coarse surface with more grip.
Basalt and granite outdoors
Split face
Broken rather than sawn, leaving a rough, natural face with deep shadow lines.
Ledger panels, wall cladding
More on choosing a finish in How to Choose Natural Stone Flooring.
Matching the stone to the room
Bathrooms and showers
Marble, limestone, travertine and basalt are all used on shower walls and bathroom floors. Underfoot, choose honed or tumbled tile, or a mosaic whose grout lines add grip. Seal the stone and keep to neutral cleaners.
Kitchens
Any of these stones can work as a backsplash. Where lemon, vinegar and wine land, calcite stones will etch over time. Choose a honed finish and accept the patina, or pick a silicate stone.
Busy floors
Granite and basalt take heavy foot traffic well. Marble and limestone work too, in a honed finish and with a doormat to keep grit off. Onyx does not belong on a busy floor.
Patios and pools
Use products made for outdoors: 3 cm travertine pavers, pool coping and flamed basalt. Many interior tiles are not rated for exterior or freeze-thaw use.
Planning outdoor work? See Travertine Paver Thickness, Pool Coping Types and the Pool Tile, Coping and Decking guide.
Living with natural stone
- Seal it. Stone sealers are impregnators. They soak in and repel water and oil rather than forming a film on top. Sealing makes stone more stain resistant, not stain proof. See How to Seal Natural Stone Tile.
- Know a stain from an etch. A stain is something absorbed into the stone, and a sealer slows it down. An etch is a dull mark where acid has reacted with the surface of a calcite stone. A sealer does not prevent etching.
- Clean it gently. Use a neutral cleaner, stone soap, or mild dish soap and warm water. Keep vinegar, lemon and other acidic cleaners off calcite stones, and skip scouring powders.
- Expect variation. It is the point of the material. Shade Variation Explained shows the range to expect.
Prefer something that never needs sealing? Marble vs Porcelain is an honest comparison.
Three things to do first
- Order samples. Stone has to be seen in your own light, next to your own finishes. Sample shipping is free. How to order samples.
- Order enough, once. Add 10 to 15% for cuts and waste, up to 20% for diagonal or complex layouts, and order the full quantity together. Stone varies between lots, and a later order may not match. Our tile calculator helps, and leftovers are worth keeping for repairs.
- Read the variation guide. Our Shade & Color Variation Guide explains the range to expect within one order.
Natural stone FAQ
What is natural stone?
Natural stone is rock quarried from the earth and cut into tile, slabs, pavers and mosaics. It includes marble, travertine, limestone, onyx, basalt, granite, quartzite, slate and sandstone. Because it is formed by nature rather than manufactured, every piece is different.
What are the main types of natural stone tile?
The main types are marble, travertine, limestone, onyx, basalt, granite, quartzite and slate. Marble, travertine and limestone make up most of our catalog. Those three and onyx are calcite stones that etch with acids. Granite, quartzite, basalt and slate are silicate stones that generally resist them.
What is the most durable natural stone?
Granite and quartzite are the hardest and most scratch resistant, because they are made mostly of quartz and, in granite, feldspar. Durability also depends on using a stone in the right place, installing it properly and sealing it. Marble and travertine have lasted for centuries in buildings where they were used well.
Does all natural stone need to be sealed?
Nearly all of it benefits. A penetrating sealer slows the absorption of water and stains. Marble, travertine, limestone and onyx should always be sealed, and dense stones such as granite and basalt benefit too. Sealing makes stone more stain resistant, not stain proof.
Why does my marble have dull spots?
Those are usually etch marks. Marble is calcite, and acids such as lemon juice, vinegar, wine and some bathroom cleaners react with the surface and leave it dull. Etching is not a stain, and sealing does not prevent it. A honed finish makes it less noticeable.
What is the difference between marble and granite?
Marble is a metamorphic stone made of calcite, about 3 on the Mohs scale, with a soft, luminous look. It is sensitive to acids. Granite is an igneous stone made mainly of quartz and feldspar, at 6 to 7 on the same scale, with a speckled grain. It resists scratching and household acids far better.
Can natural stone be used outdoors?
Yes, with the right product. Thick pavers, pool coping and textured finishes are made for outdoor use. Many interior tiles are not rated for exterior or freeze-thaw conditions, so check the product page for your climate before ordering.
Is natural stone better than porcelain?
It depends on what you value. Natural stone is unique from piece to piece and develops character over time, but it needs sealing and the right cleaners. Porcelain is consistent and needs very little care. Many projects use both.
Sources
- Natural Stone Institute, Care and Cleaning of Natural Stone: calcareous and siliceous stone, cleaners, sealing.
- Geology.com rock profiles for marble, limestone, granite, basalt, quartzite, slate and sandstone, and the Mohs hardness scale.
- Encyclopaedia Britannica: travertine, onyx marble and the Colosseum.
- Use Natural Stone (Natural Stone Institute): travertine and the minerals in stone.
Find your stone
Browse the natural stone collection, or order a few samples and see them at home first. Sample shipping is free.
Questions? Talk to a tile specialist: 855-797-8453, Mon–Fri 8:30 AM–5:00 PM PT
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