Natural Stones

For centuries, natural stone has been the material of choice in Australian architecture, valued for its authenticity, durability and timeless character.

What is Natural Stone?

Natural stone refers to any rock or mineral substance that has taken shape through geological processes over millions of years. It is pulled directly from the earth and then cut or shaped for use in construction, landscaping and decorative applications.

Natural stones fall into three geological categories:

• Igneous - Cooled from molten rock. Hard, dense and low in porosity. Examples: granite, bluestone.
• Sedimentary - Laid down over time from organic material, minerals and compressed sediment. Softer and more porous, with a layered surface character. Examples: limestone, sandstone, travertine.
• Metamorphic - Pre-existing rock reshaped by extreme heat and pressure. Recognised for distinctive veining and crystalline texture. Examples: marble, slatestone.

What are the Types of Natural Stone?

Stone Centre's natural stone range spans seven stone types, each carrying its own geological background, surface character and physical makeup.

• Travertine forms when calcium carbonate-rich groundwater precipitates and solidifies. The result is a sedimentary stone with a naturally pitted surface and a wide tonal range.
• Limestone is a fine-grained sedimentary stone, its composition drawn from calcium carbonate sourced through marine organisms and mineral deposits over time.
• Marble comes about when limestone undergoes recrystallisation under sufficient heat and pressure. The process yields a metamorphic stone that is both denser and harder than its source material, marked by the veining it is widely known for.
• Granite takes shape deep within the earth's crust as magma cools slowly over time. The outcome is an igneous stone with large mineral crystals, a speckled surface, low porosity and strong resistance to surface wear.
• Sandstone is built from sand grains that compact and bind together through geological time. The surface has an open, grained texture, with tonal character shaped by the mineral composition of its binding material.
• Bluestone is a dense, fine-grained igneous stone of basalt origin. Its hardness and very low porosity put it among the more structurally reliable stones in the range.
• Slatestone is a fine-grained metamorphic stone that originates from compressed clay or volcanic ash. Its layered internal structure causes it to cleave naturally, giving the stone its recognisable textured face.

What are the Finishes Available in Natural Stone?

Surface finish shapes how a stone reads tonally, how it feels underfoot or to the touch, and how it performs day to day. The natural stone range is available in the following finishes:

• Honed - Ground to a smooth, consistent matte. Veining and tonal variation remain visible; no gloss or reflectivity.
• Polished - Buffed to a high gloss. Brings out the full depth of tonal variation and veining.
• Natural Split - Cleaved along the stone's natural bedding plane. Irregular, textured face - no two pieces identical. 
• Tumbled - Mechanically tumbled to soften edges and surfaces. Produces a worn, aged character. 
• Sandblasted - Fine abrasive applied under pressure. Even, lightly textured surface through which tonal character reads clearly. 
• Exfoliated (Flamed) - Intense heat causes outer crystals to burst, leaving a rough, textured surface. 
• Antique - A surface treatment that produces a weathered, characterful finish. 
• Filled - Open pits and voids are filled for a more consistent, even surface.

How to Seal and Maintain Natural Stone?

All natural stone carries some degree of porosity and needs sealing prior to installation and at intervals after. How often you reseal and what product you use depends on the stone type, its finish and the conditions it faces.

• Before installation - Dip-sealing all faces and edges before laying is widely recommended. Unsealed stone faces, particularly porous types, can pick up staining during the bedding process; pre-sealing removes that risk.
• After installation - Once installation is done and the surface has been cleaned, apply a final coat of penetrating natural stone sealer.
• Ongoing maintenance - Reseal every two to three years, adjusted for use and exposure. Surfaces that see heavier traffic or weathering may need attention sooner.
• Cleaning - A pH-neutral stone cleaner diluted in warm water, worked across the surface with a soft mop or brush and rinsed off thoroughly, handles routine cleaning well. Acid-based products - vinegar, citrus cleaners and low-pH bathroom products will permanently etch the surface. Bleach and ammonia-based cleaners should also be kept away from natural stone.
• Weed and joint management - On natural stone paving, joints need periodic inspection. Any weed or moss growth should be cleared promptly - left alone, root systems work their way into jointing compound and can gradually sift individual pieces out of position.

How to Choose the Right Natural Stone?

Picking the right stone comes down to matching the physical properties of the material to the demands of the space.

• Hardness and density - Igneous stones such as granite and bluestone are the densest and hardest options. Metamorphic stones like marble sit in the middle ground. Sedimentary stones such as limestone, sandstone and travertine are generally softer and call for more regular upkeep.
• Porosity - A more porous stone absorbs liquid more readily and needs more consistent sealing attention. Travertine, limestone and sandstone are at the more porous end. Granite and bluestone sit at the opposite end of that scale.
• Tonal range - Stone tones shift by type and by deposit. Looking at samples in the actual installation setting rather than a showroom or warehouse gives a far more reliable read of how the stone will look under the light conditions of that space.
• Surface finish - Honed and tumbled finishes tend to be more forgiving when it comes to surface marks. Textured options like natural split and sandblasted hold their character well under regular use.
• Format and gauge - Tile gauge (12–15mm) suits installation on a prepared concrete subfloor or substrate. Paver gauge (30mm) is the right specification for ground-level exterior paving that carries foot or vehicle load.