Crystal Hill Area

brochure Kofa - Crystal Hill Area

Crystal Hill Area in Kofa National Wildlife Refuge (NWR) in Arizona. Published by the U.S. Fish & Wildlife Service (USFWS).

U.S. Fish U.S. Fish&&Wildlife Wildlife Service Service Crystal Hill Area Kofa National Wildlife Refuge Crystal Hill, located in the northwest corner of Kofa National Wildlife Refuge in the Livingston Hills, is the only area within the refuge where recreational rock or mineral collecting is permitted. Quartz crystals are hidden in the washes and on the rocky slopes of Crystal Hill, making this an ideal location for rockhounding or collecting. While searching for quartz crystals at the top of the hill, visitors can also enjoy the 360 degree view of the surrounding area. Creation of the Mountains The mountains of Kofa National Wildlife Refuge, which rise abruptly from the flat desert, are characteristic of the Basin and Range Province which covers much of the western United States and extends into northwestern Mexico. In this physiographic region, the Earth’s crust and upper mantle thinned and cracked as they were stretched and pulled apart. Quartz Formation Quartz, belonging to the class of silicates, comprises approximately 12 percent of the Earth’s crust. It is produced when the two most abundant elements in the surface of the Earth, oxygen and silicon, bond. Quartz crystallizes when volcanic magma cools and becomes solid. A fault created by crustal movement. Illustration from http://clasfaculty.ucdenver.edu/ callen/1202/Battle/Build/Faulting/Faulting.html This crustal movement created faults and eventually led to the creation of mountains and valleys as the Earth’s surface uplifted on the upthrown side of the fault and down-dropped on the lower side. Over time, the block-faulted mountains weathered and eroded. Volcanic episodes also occurred within the refuge and thus the mountain ranges of Kofa National Wildlife Refuge contain old lava layers and volcanic rocks, such as basalt, volcanic tuff and obsidian. Quartz appears in a variety of forms and shapes and varies from being clear to almost opaque. It may be found in the form of large grains, crystals or veins. Crystals can appear either as a single point or in a cluster. Pure quartz is white or colorless, while other types of quartz may be rose, yellow, green, blue, violet, brown, or black depending on the trace elements they contain. The Livingston Hills are known to have both quartz veins and crystals. Some veins in the hills contain tourmaline and pyrite, two other minerals. Most of the quartz crystals found at Crystal Hill are either clear or milky white. Rockhounding and Collecting on the Refuge When searching for quartz crystals on the refuge, it is important to remember that recreational (noncommercial) rock or mineral collecting is not permitted beyond the boundaries of the Crystal Hill Area (see map). Collection of rocks is limited to 10 specimens or 10 pounds (whichever occurs first) in any 12-month period. Rock or mineral collection is limited to materials that are exposed and collectable without the use of tools, including metal detectors. Digging is prohibited. Please see the Kofa National Wildlife Refuge leaflet Public Use and Hunting Regulations for more information about regulations. For Further Information U.S. Fish and Wildlife Service Kofa National Wildlife Refuge 9300 East 28th Street Yuma, AZ 85365 928/783-7861 Monday–Friday: 8:00 a.m.–4:30 p.m. February 2014 Front, illustration of a desert bighorn. Illustration by Elizabeth Montgomery Desert bighorn at Kofa National Wildlife Refuge. / USFWS.

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