Marble

Marble is born of pressure. Limestone, subjected to heat and geological force, recrystallises into the veined, luminous stone specifiers have reached for since antiquity. No two blocks read the same way, which is precisely its appeal, and its limitation.

• Hardness: Mohs 3-4
• Porosity: moderate
• Acid sensitivity: high, etches on contact with lemon, vinegar or wine

It suits feature walls, low-traffic flooring, bathroom surrounds, and bookmatched statement panels, anywhere it's spared regular contact with acid. Kitchen counters ask more of marble than it can reliably give, unless it's sealed and looked after with real consistency.

Granite

Where marble is sculpted by pressure, granite is forged by fire. An igneous stone of interlocking quartz, feldspar, and mica, it carries a density that marble simply cannot match.

• Hardness: Mohs 6-7
• Porosity: low, typically under 0.4% water absorption
• Acid sensitivity: low, resists most kitchen acids

It performs beautifully as a kitchen countertop, across heavy-traffic floors, and on exterior cladding, needing little beyond an occasional reseal to guard against staining over time.

Quartzite

True quartzite is sandstone taken to its geological extreme, recrystallised under such pressure that it becomes almost pure quartz. It is also the family most frequently misrepresented in the trade, a distinction worth its own attention. A great deal of what circulates as "soft quartzite" is, in fact, dolomitic marble, a softer stone wearing quartzite's name.

Two simple tests settle the matter: a steel blade will not mark true quartzite but will mark marble, and a drop of acid etches marble while quartzite remains unaffected. Worth confirming before specification, not after installation.

• Hardness: Mohs 7
• Porosity: low, in genuine quartzite
• Acid sensitivity: low, resists etching

It's the natural choice wherever a client wants marble's character paired with granite's endurance, provided the label can be trusted.

Limestone

Limestone is sedimentary in origin, calcium carbonate laid down over time, often carrying the fossilised trace of what the ocean once held. Its density varies considerably from quarry to quarry.

• Hardness: Mohs 3-4
• Porosity: moderate to high
• Acid sensitivity: high, comparable to marble

It lends itself to cladding and honed interior flooring, wherever it's kept clear of regular acid exposure. Kitchen counters and unsealed exteriors in wet climates are where it tends to struggle.

Travertine

Travertine carries its history visibly. A banded form of limestone, shaped by mineral-rich spring water, its surface voids are not a flaw but a signature, refined or left open depending on the finish desired.

• Hardness: Mohs 3-4
• Porosity: high when unfilled
• Acid sensitivity: high

Filled and honed, it excels as flooring and wall cladding, and as a pool surround finished for slip resistance. Polished travertine in wet conditions, or unfilled stone left unsealed near frequent spills, is where problems begin.

Onyx

Onyx is the most theatrical of the natural stones, a banded, translucent form of calcite that transforms under light. That same delicacy that makes it luminous also makes it the most fragile stone in this guide.

• Hardness: Mohs 3-4, lower impact resistance than other calcite-based stones
• Porosity: moderate, though impact matters more than liquid exposure
• Acid sensitivity: high

It belongs on backlit feature walls, bar fronts, and considered decorative accents, never on floors, countertops, or anywhere required to bear real weight.

Sandstone

Sandstone is quartz grains bound by a natural cement, silica, calcite, or iron oxide, and it is this binding mineral, more than the quartz itself, that determines how the stone performs.

• Hardness: Mohs 6-7 if silica-cemented, softer if calcite-cemented, this varies by source
• Porosity: often high, depending on the cementing mineral
• Acid sensitivity: variable, calcite-cemented sandstone etches, silica-cemented sandstone resists

It remains a dependable choice for exterior cladding, landscaping, and indoor-outdoor flooring, provided the cement type has been confirmed for that particular quarry.