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How to Identify Quartzite

Quartzite is sandstone that has been turned into solid rock under heat and pressure over time. The heat and pressure break through the quartz grains instead of around them, as is the case with sandstone. The term "quartzite" implies high quartz content with a high degree of hardening.

Instructions

- 1
  Observe the color of quartzite. White to grey is the color of pure quartzite but it can develop in a wide variety of hues depending on the impurity level. The most common of these is iron oxide, causing the quartzite to be pink to red.
- 2
  Study the composition of quartzite. Most quartzite is at least 90 percent quartz but some is 99 percent pure, making it the purest naturally-occurring source of silica on Earth.
- 3
  Examine the structure of quartzite microscopically. The individual grains of quartz and former cementing material have recrystallized, and whole pieces may show individual sand grains with quartz overgrowths. In other samples the quartzite has been crushed, resulting in small, irregular crystalline fragments.
- 4
  Learn some of the specific physical properties of quartzite. It is a 7 on the Mohr hardness scale, has a density of about 2.7 times that of water and ranges from transparent to opaque with a waxy to vitreous luster.
- 5
  Find large quantities of quartzite in the Morenci Copper Mine of Arizona, eastern South Dakota, southwest Minnesota, the Wasatch Range in Utah and the Baraboo Hills in Wisconsin. Other noteworthy locations include southwestern Greenland, Mysore, India and Sierra de Gador, Spain.

Rocks & Minerals