It is often difficult or impossible to differentiate quartz arenite from quartzite. The name "quartz arenite" is a more appropriate and less confusing name for these rocks. This usage is falling out of favor but remains in older textbooks and other older publications. Today most geologists who use the word "quartzite" are referring to rocks that they believe are metamorphic and composed almost entirely of quartz.Ī few geologists use the word "quartzite" for sedimentary rocks that have an exceptionally high quartz content. Geologists have used the name "quartzite" in a few different ways, each with a slightly different meaning. John, used here under a Creative Commons license. The quarry is in the Elmers Rock Greenstone Belt, Wyoming. This specimen measures about 7 centimeters across and was collected from a small abandoned quarry where the flaggy rocks were produced and cut for use as decorative stones. Other impurities can cause quartzite to be yellow, orange, brown, green, or blue.įuchsitic Quartzite: A specimen of quartzite that contains significant amounts of green fuchsite, a chromium-rich muscovite mica.
Some rock units that are stained by iron can be pink, red, or purple. Quartzite is usually white to gray in color. This is a characteristic that separates true quartzite from sandstone. It is so tough that it breaks through the quartz grains rather than breaking along the boundaries between them. The interlocking crystalline structure of quartzite makes it a hard, tough, durable rock. Photograph by Jackdann88, used here under a Creative Commons license. The interlocking nature of the grains gives quartzite its incredible durability. The important thing to notice is how they fit together in a tight interlocking network. The quartz grains in this view range in color from white to gray to black depending upon their optical orientation. Quartzite Under a Microscope: A specimen of the Bo Quartzite collected near South Troms, Norway, observed through a microscope in thin-section under cross-polarized light.
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