Similar to me, many people really like the mineral quartz – and for excellent reasons. Quartz is a major building block of my favorite landscapes, found in the granitic rocks forming the Andes Mountains of South America and the Sierra Nevada of California; the sandy beaches along the California coast; the vast sand dunes of Death Valley and the Sahara Desert, and the Red Rock geologic units in Arches, Capital Reef, Zion, Canyonlands and many more fabulous parks of the US Southwest. I’m quite found of lavender-colored amethyst crystals – and I appreciate the quartz crystal inside my wristwatch and all the essential electronic tools in our lives. Maybe you are a quartz fan also?
My appreciation for quartz was triggered recently when I read a blog post by Marli Miller, Five Awesome Minerals – for rocks and landscapes. Quartz is in her list of the top five, and along with interesting text about minerals, she includes great photos; you can check out her post here: https://geologictimepics.com/2020/11/30/five-awesome-minerals-for-rocks-and-landscapes/
There are many curious and unusual facts about quartz. It can be found in all three types of rock: igneous, metamorphic and sedimentary. Not surprisingly, it is among the most common of the more than 5,500 recognized minerals on the Earth’s crust, comprising about 12% by volume. Quartz is very hard, with a strong and stable configuration of silica and oxygen. Quartz crystals are six-sided prisms, joined at perfect 60 degree angles, with six-sided pyramids at each end. Well-formed crystals grow where there is sufficient space for unconstrained growth, such as inside the voids of geodes, the round cavities found in various rocks that are lined with crystallized minerals. Quartz can also precipitate from solutions, forming compact masses, such as in the extensive veins that can cut across granitic rocks, and it is a common cement that binds sand, silt and clay particles together into sedimentary rocks.
The purest quartz, sometimes called rock crystal, is colorless and transparent. Small additions of various impurities that are incorporated into the crystal structure produce diverse hues, some of which create highly sought semi-precious gemstones. These include the purples of amethysts produced by ferric iron, pinks of rose quartz from manganese or titanium, yellows of citrine from colloidal iron hydrates, and grays of smoky quartz from traces amounts of aluminum. The microcrystalline variety of quartz, known as chalcedony, is usually banded. Found in varieties known as agate, jasper, onyx, Tiger’s eye, carnelian, and flint or chert, this form typically precipitates from watery solutions in geodes formed in lava.
Quartz crystallizes directly from molten magma, either in volcanic rocks such as rhyolites from volcanic eruptions, or from plutonic rocks that cool slowly deep underground, like granites. It can also precipitate from hot water circulating through granitic rocks in hydrothermal veins, where it can be associated with gold and silver ore (e.g., the enormous wealth of gold removed from the Mother Lode of the Sierra Nevada was found in quartz veins). The hardness of quartz makes it extremely resistant to weathering, creating the stable quartz sands of marine or desert sands.
Quartz crystals are stable under metamorphic conditions of heat and pressure. Quartz-rich sandstones metamorphose into hard quartzite. Carrara marble from Italy, the famous stone preferred by Michelangelo and other sculptors for their artworks, was metamorphosed from limestone, but also contains unusually clear and tiny quartz crystals.
Mountains and Deserts
In a simple but elegant cycle, rocks are broken down into fragments through weathering and then the bits are carried away by erosion – these sediments are eventually consolidated into new rock – and after more time passes the younger rocks break apart, and the cycle to form new rocks begins again. Since quartz is highly resistant to weathering, and other minerals disintegrate more rapidly, quartz sand can becomes quite abundant over time. These sands are carried by wind or water onto ocean beaches or into dune fields. When large quantities accumulate and then become consolidated, the sandstones that form an estimated 25 percent of sedimentary rocks will develop. Eventually the sandstones will once again be broken down into fragments and dispersed, beginning another cycle that can eventually create more sandstone.
Many mountain ranges, including the Andes Mountains and the Sierra Nevada, are underlain by enormous bodies of quartz-rich granitic rocks. These rocks were created by large pools of magma deep underground that cooled into what are known as batholiths, or plutons. After being folded, faulted and uplifted from tectonic processes, the batholiths can be exposed on the surface to form rugged mountain ranges. Older rock that was initially intruded by the magma body can also be exposed along with the granitic rock. A fabulous example of this is in Torres del Paine National Park in the Patagonia region of Chile, where a Tertiary (Miocene) granitic batholith intruded into much older (Cretaceous) sedimentary rock. Now, the dark sedimentary “caps” on the iconic Cuernos del Paine (Horns of Paine) are eroding away more rapidly than the light gray and strong granitic rock. (A trip to Patagonia and seeing these majestic mountains was one of the highlights of my life!)
As mountain ranges are eroded away over millions of years, the enormous amounts of quartz sand that develop can accumulate in gigantic desert dune fields. These created the spectacular rocks in the US Southwest, where colorful sandstones are found in the Red Rock country of the Colorado Plateau; you can learn more about this topic in my post here: https://roseannechambers.com/red-rock-country-on-the-colorado-plateau/ . These sandstones have a fascinating history. (Note: the brief summary below is from one of my favorite books: Ancient Landscapes of the Colorado Plateau by Ron Blakely and Wayne Ranney (2008). The text, maps, and photographs in this book are exceptional.)
The Red Rock quartz sands were derived from ancient mountain ranges. Among the sources were the Ancestral Rocky Mountains, which rose in the same location as the Rocky Mountains today, but existed from about 315 million to 165 million years ago. The sand that accumulated as these mountains weathered away formed many of the colorful rocks in famous Monument Valley, in the Grand Canyon and Sedona regions, in the Needles district of Canyonlands National Park, and many other locations within the Colorado Plateau that are all of late Paleozoic age (Pennsylvanian and Permian).
Millions of years later, during the early and middle Jurassic, when dinosaurs were roaming across the landscape, vast arid deserts developed in the Colorado Plateau region. These deserts were filled by massive amounts of sand from the lofty Appalachian mountain chain that once extended from approximately New England to central Mexico. The now low mountains were once as high and rugged as the modern Rocky Mountains (and, I haven’t visited them on the East coast yet, but hope to someday). As the Appalachians were gradually lowered by weathering and erosion, westward flowing rivers delivered eroded sediments across the lands that were destined to become the US Southwest.
Over a period of about 45 million years in the Jurassic, three major sand seas developed in the Colorado Plateau region. The first of these formed the Wingate sandstone with spectacular cross-beds from ancient dunes found in Capital Reef and Canyonlands national parks, and across the Navajo Indian Reservation. The next major period of sand dune formation created the Navajo Sandstone – one of the greatest windblown sand accumulations on Earth. Around 190 million years ago Navajo sands accumulated over much of the Colorado Plateau region, as well as into southern Arizona, Nevada and into California The Navajo Sandstone forms the spectacular cross-bedded exposures in Zion and Capital Reef National Parks, as well as many other parks in the region. The third and final major sand sea resulted in placement of the Entrada Sandstone. The natural arches that have developed in Arches National Park are among the most famous of the Entrada Sandstone outcrops.
Finally, I’m also a quartz fan because I love to visit modern deserts. I have happily wandered through the dune fields of Death Valley National Park and in the vast expanses of the Sahara Desert during months of fieldwork in southern Egypt in the 1980s. I love the stark beauty and the emptiness of these landscapes – and the fine quartz sand. Ocean beaches, where crashing waves are continuing to break down rock fragments into the rounded white grains of quartz sand, are also my favorites.
Quartz sand is a valuable resource in many industrial applications, and although there are vast quantities of this material on our planet, the preferred type isn’t always in the right place at the right time. This leads to the need for some countries – including those on the sand-rich Arabian Peninsula — to import enormous quantities of sand from countries like Australia. You can read more about sand imports in my post here: https://roseannechambers.com/desert-countries-import-sand/ )
Small slices of quartz in time pieces can keep extremely accurate time. This is because quartz is strongly piezoelectric – it produces electricity when mechanically compressed in a certain crystallographic direction. Quartz crystals can vibrate at a very precise rate, which regulates the movement of a timepiece. Other applications for quartz crystals include a wide variety of electronics, including computers and cell phones.
Piezoelectric effects were initially recognized by the French physicists, Jacques and Pierre Curie, in 1880. The first wide use of quartz crystals to take advantage of this property was during World War 1 as a component of sonar devices that used sound waves to calculate distances to enemy submarines. Subsequently, quartz was used in other equipment to detect and produce sounds, including for phonographs (aka record players, if you are a few decades younger than I).
When World War II disrupted the quartz crystal supply chain, scientists in several nations attempted to synthesize quartz. A German mineralogist named Richard Nacken established the groundwork in the 1930s and 1940s, and after the war many laboratories in the US worked to expand Nacken’s techniques to make quartz crystals. By the 1950s synthetic quartz crystals were being produced on an industrial scale in thick-walled steel pressure vessels, or autoclaves, in which temperature and pressure could be controlled for optimal crystal growth conditions. Synthesis techniques can now successfully create quartz crystals with precise frequencies for specific functions, so most of the quartz used in electronics is synthetic.
Natural Crystals and Market Demands
As valuable as synthetic quartz has become, natural quartz for gemstone uses and for crystal healing rituals are in high demand. Healing properties have been attributed to quartz crystals by many cultures over thousands of years. These include powers to balance emotions, boost low energy, release blocked energy, and provide healing vibrations to a person. The placebo effect apparently applies, as studies have shown there is no scientific basis for these healing powers. Nonetheless, in the past few years the booming wellness industry in the US has significantly increased demand for crystals of all types. Crystals have become a billion dollar business – and that is creating significant problems around the globe.
Sadly, similar to other natural mineral resources I have written about in my posts, there are significant environmental and human costs for procuring quartz and other types of crystals today – and for the most part these are not recognized nor acknowledged by wealthy consumers. (Learn more in Dark crystals: the brutal reality behind a booming wellness craze by McClure, 2019, in Sources, below.)
The demand for crystals has prompted “artisanal mining” in many developing countries. Operated on a small scale by families or communities, these result in significant environmental damage and hazardous conditions for workers, sometimes including children. In deep open pits or networks of narrow tunnels, all of which are subject to catastrophic collapses, rough mineral masses are dislodged with picks and shovels and dragged out of the depths. The returns that the locals receive for exporting their resources are meager – reportedly, for rose quartz mined in Madagascar, it is around a penny per ounce for the miner, an income that can be 0.1% of the final retail price at a shop or mineral show in the US.
Better to find your own quartz crystals where collecting is allowed on public lands (they occur in abundance in California, Nevada, and many other US states) — or best of all, to simply appreciate quartz in the beach sands, sandstones, and granites that are part of so many amazing and powerful landscapes on our planet Earth.
Blakely, R. and Ranney, W., 2008, Ancient Landscapes of the Colorado Plateau; Grand Canyon Association
McClure, T., 2019, Dark crystals: the brutal reality behind a booming wellness craze; The Guardian: https://www.theguardian.com/lifeandstyle/2019/sep/17/healing-crystals-wellness-mining-madagascar
Photo of Half Dome in Yosemite Valley by Jon Sullivan (PD Photo.org); https://en.wikipedia.org/wiki/Granite#/media/File:Yosemite_20_bg_090404.jpg
Photo of an amethyst geode that formed when large crystals grew in open spaces inside the rock. https://en.wikipedia.org/wiki/Amethyst#/media/File:Druse.jpg
Photo of amethyst from Siberia by Marie-Lan Tay Pamart: https://commons.wikimedia.org/wiki/File:Amethyst_Siberia_MNHN_Min%C3%A9ralogie.jpg
Photo of a synthetic quartz crystal grown by the hydrothermal method, about 19 cm long and weighing about 127 grams by Didier Descouens — https://en.wikipedia.org/wiki/Quartz#/media/File:Quartz_synthese.jpg
My photos of Patagonia, Canyonlands NP, and Arches NP
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