In current commercial usage, "quartz" almost always refers not to a mineral cut into slabs, but to an industrial composite made by mixing ground quartz with polymer resins. It's a distinction many clients — and more than a few designers — don't make, and it's a common source of mismatched expectations: these materials behave differently from natural stone, with specific advantages and limits worth knowing before specifying them in a spec sheet.
Agglomerated quartz: the Italian invention nobody calls Italian
The process that made agglomerated quartz possible — technically known as Bretonstone — was patented in 1963 by the Treviso-based company Breton, not by chance in the same industrial district that produces machinery for working natural stone. The Bretonstone process compresses, under vacuum and vibration, a mix made up of about 90-93% ground quartz (crystalline silica, the same mineral that gives granite its hardness) and the remaining 7-10% unsaturated polyester resin, pigments and a polymerisation catalyst. The result is a slab with almost no porosity, flexural strength higher than many natural stones, and a colour and veining uniformity no quarry can guarantee batch after batch. Brands such as Silestone (Cosentino, Spain) and Caesarstone (Israel) made this product the standard for residential kitchen worktops across much of the Western world from the 1990s onward.
The technical limitation of agglomerated quartz is precisely its organic component: the polymer resin degrades under prolonged UV exposure (which is why these products aren't recommended for unprotected exterior facades) and can't tolerate direct contact with very hot surfaces — a pan straight from the stove can cause localised thermal shock that granite or marble would absorb without consequence. In addition, dry-cutting crystalline quartz releases a high concentration of respirable silica dust: an occupational risk — accelerated silicosis among industry workers — that has, in recent years, led to stricter regulations mandating wet cutting in several countries, Australia foremost after a wave of diagnosed cases among workers in the sector.
Sintered stoneware: stone "fired" like a ceramic
A conceptually different family of products is large-format sintered porcelain stoneware — brands such as Dekton (Cosentino), Neolith (TheSize) and Laminam — which does away with the organic component entirely. The process, borrowed from the ceramics industry but scaled up to large-format slabs (up to 3.20 × 1.60 metres, thicknesses from 3 to 20 mm), compresses a mix of minerals (feldspars, silica, clays, oxides) and subjects it to sintering — firing at temperatures above 1,200°C that partially fuses the mineral grains into an almost glassy matrix, extremely dense and free of open porosity. The result has a mineralogical composition much closer to natural stone than agglomerated quartz (no resin), combined with mechanical, chemical and UV resistance higher than any untreated natural stone: these slabs suit exterior ventilated facades, kitchen surfaces in direct contact with heat, and high-traffic flooring.
When to choose one, the other, or the real material
The choice between natural stone and its industrial substitutes is never purely technical: it's cultural too. An agglomerated-quartz worktop offers more predictable performance and generally lower cost than natural marble of comparable appearance, but with an intrinsically different service life — it doesn't age, for better (no wear patina) and for worse (no visible history in the material). Sintered stoneware today competes directly with natural stone even on facades, where its reduced weight (a 6 mm slab weighs a fraction of a 30 mm marble slab) drastically simplifies anchoring systems. Environmentally, though, the calculation isn't clear-cut: the sintering process requires high industrial temperatures comparable to firing brick, so the embodied carbon of these surfaces can end up higher than that of local natural stone, despite the absence of quarry impact. There's no single right answer: there's a specific project, with exposure conditions, budget and expected service life that have to be weighed case by case.