Tectosilicate Mineral Quartz

Associated Smithsonian Expert: Michael A. Wise, Ph.D.

Michael Wise investigates granite and pegmatite dikes that intruded into metasedimentary rocks near Mount Antero, Colorado.

Courtesy of Jennifer C. Kelly

Dr. Michael Wise is a geologist and an expert on pegmatites, which are coarse-grained igneous rocks rich in the minerals quartz and feldspar. A native of Smithfield in southeastern Virginia, Dr. Wise first got interested in mineralogy as an undergraduate at the University of Virginia, when rock-hunting trips to central Virginia and North Carolina strengthened his interest in this type of rock. He obtained his doctorate from the University of Manitoba in Canada in 1987 and joined the Smithsonian National Museum of Natural History Department of Mineral Sciences one year later. He has traveled widely in the Appalachian mountains of the eastern United States to study pegmatites, which are good sources of not only semiprecious gemstones such as aquamarine, rose quartz, and topaz, but also rare elements, such as beryllium, lithium, and cesium, with important economic applications. His research has also taken him to Nevada, Colorado, California, and the Northwest Territories of Canada. In the laboratory, he uses a scanning electron microscope, cathodoluminescence microscope, X-ray diffractometer, and other tools to investigate the composition, crystal structure, and evolution of pegmatites.

Meet our associated expert

This image was obtained from the Smithsonian Institution. The image or its contents may be protected by international copyright laws.

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Detailed geologic time scale.
From the Geologic Society of America, used with permission

About Morrison Quarry

The continental crust in Colorado was constructed from several island chains that collided and merged together about 1.75 billion years ago. It was then metamorphosed at depth under heat and pressure, and magma was injected through cracks in the rock. After several million years of erosion the rocks of the Morrison Quarry became exposed at the surface. Layers of sandstone were deposited directly on top of the exposed rocks forming what is known as the "Great Unconformity," a 1.4-billion-year gap missing between one rock layer and the next. These rocks were likely uplifted during the formation of the Ancestral Rockies between 320 and 270 million years ago. The Ancestral Rockies were eventually eroded away, buried by sediments and flooded by shallow oceans. They were brought to the surface once again during the growth of the current Rocky Mountains.

Artist interpretation of the Laramide Orogeny, which led to the creation of the Rocky Mountains in the Western United States.
Image created by Karen Carr Studio, Inc., used with permission

About Silicate Minerals

Silicon and oxygen are two of the most common elements on Earth. Together, they make up nearly 75 percent of the Earth's crust, so it is no surprise that they play major roles in forming many of the minerals that we see in rocks. The silicon atom, which has four electrons in its outermost region, likes to form chemical bonds with oxygen atoms, which are attracted to extra electrons. Thus, silicon and oxygen, together with some of the metallic elements, can combine to make hundreds of different minerals. For example, quartz has two oxygen atoms for every silicon atom, and feldspar has two or three silicon atoms grouped with eight oxygen atoms and a few metal atoms. About half of the most common minerals found on Earth belong to the silicate group, as do some beautiful gemstones such as amethyst, opal, and topaz.