Quartz

Summary

Quartz is the silicon dioxide mineral found in granite, sandstone, and sand, and the name used for engineered quartz surfaces made of stone aggregate bound in resin. Engineered quartz is a manufactured product with its own production process, so specify it as a surfacing material and treat fabrication dust as a silica hazard.

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Quartz (mineral): silicon dioxide (SiO2) in a framework of silicon-oxygen tetrahedra
Alpha and beta quartz: the room-temperature and high-temperature forms; beta converts to alpha at 573 degrees C
Engineered quartz: slab surfacing made of stone aggregates and polyester resin
Bretonstone: the vibrocompression process developed by Breton

History and demand

Invention

Breton, founded in 1963 in Castello di Godego, Treviso, by Marcello Toncelli, began as a maker of natural stone machinery and calls its engineered product the first mineral surface produced on an industrial scale
Sources disagree on when the engineered-stone process was developed: one places it in the early 1970s, another credits Breton with introducing the resin-bound composite in the late 1980s
The process uses vibrocompression under vacuum: the mix is vibrated, pressed, and heated

First uses in construction

Engineered quartz slabs entered building use as counter and surfacing material after the Breton process; the sources checked give no dated first project
No dated first construction use of the quartz mineral itself was found in the sources checked

Sourcing

Quartz mineral: Brazil is the most frequently named source; the Spruce Pine district of North Carolina is a major source of high-purity quartz
Engineered quartz is made in slab plants; the sources checked did not give a verified producer-country breakdown

Demand trend

No dated demand figure was found in the sources checked

Composition and production

Raw materials

Engineered quartz: about 93 percent stone aggregates and 7 percent polyester resin by weight in one description; a manufacturer also puts resin at about 7 percent

Manufacturing process

Aggregate and resin are mixed, then vibrated, pressed, and heated under vacuum into slabs

Properties

Physical

Hardness: Mohs 7 for the quartz mineral
Specific gravity: about 2.65 for quartz (about 165 lb/ft3)

Standards

Material specifications

ASTM C616: quartz-based natural dimension stone, such as sandstone and quartzite

Uses in buildings

Building elements

Countertops: engineered quartz slabs for counter and vanity tops
Wall Cladding: quartz-based natural stone panels

Pros and cons

Pros

Consistent color and pattern in engineered slabs

Cons

Less tolerant of extreme heat than granite
Cutting and grinding releases respirable crystalline silica; OSHA sets a limit of 50 micrograms per cubic meter as an 8-hour average

Manufacturing and cost

Main manufacturers and suppliers

Trade association: Natural Stone Institute.

Sources

Wikipedia: Quartz, https://en.wikipedia.org/wiki/Quartz
Breton: the story of Bretonstone, https://breton.it/services/articles/story-of-bretonstone
Stone World: more than three decades of progression, https://www.stoneworld.com/articles/86906-more-than-three-decades-of-progression-
MSI: what is quartz and how is it made, https://www.msistone.com/blogs/post/2016/12/01/tips-from-the-trade-what-is-quartz-and-how-is-it-made.aspx
OSHA: silica hazard alert, https://www.osha.gov/dts/hazardalerts/silica_hazard_alert.html
Image: Unknown Quartz crystal 67.JPG, Jon Zander (Digon3), CC BY-SA 3.0, https://commons.wikimedia.org/wiki/File:Unknown_Quartz_crystal_67.JPG