Colorado Rocks & Minerals: A Field Guide to the Centennial State (Rocks & Minerals Identification Guides) - Softcover

Über die Autorin bzw. den Autor

Dan R. Lynch has a degree in graphic design with emphasis on photography from the University of Minnesota Duluth. But before his love of the arts came a passion for rocks and minerals, developed during his lifetime growing up in his parents’ rock shop in Two Harbors, Minnesota. Combining the two aspects of his life seemed a natural choice and he enjoys researching, writing about, and taking photographs of rocks and minerals. Working with his father, Bob Lynch, a respected veteran of Lake Superior’s agate-collecting community, Dan spearheads their series of rock and mineral field guides―definitive guidebooks that help amateurs “decode” the complexities of geology and mineralogy. He also takes special care to ensure that his photographs compliment the text and always represent each rock or mineral exactly as it appears in person. He currently works as a writer and photographer in Madison, Wisconsin, with his beautiful wife, Julie. Bob Lynch is a lapidary and jeweler living and working in Two Harbors, Minnesota. He has been cutting and polishing rocks and minerals since 1973, when he desired more variation in gemstones for his work with jewelry. When he moved from Douglas, Arizona, to Two Harbors in 1982, his eyes were opened to Lake Superior’s entirely new world of minerals. In 1992, Bob and his wife Nancy, whom he taught the art of jewelry making, acquired Agate City Rock Shop, a family business founded by Nancy’s grandfather, Art Rafn, in 1962. Since the shop’s revitalization, Bob has made a name for himself as a highly acclaimed agate polisher and as an expert resource for curious collectors seeking advice. Now, the two jewelers keep Agate City Rocks and Gifts open year-round and are the leading source for Lake Superior agates, with more on display and for sale than any other shop in the country.

Auszug. © Genehmigter Nachdruck. Alle Rechte vorbehalten.

Quartz

Hardness: 7 Streak: White

Environment: All environments

What to look for: Very abundant, light-colored, very hard crystals, masses, veins or pebbles

Size: Quartz ranges in size from masses the size of a basketball to crystal points smaller than a pea

Color: Colorless to white, gray, yellow to brown, purple, pink

Occurrence: Very common

Notes: Quartz is the single most abundant mineral on the planet, and it is absolutely essential for amateur and professional collectors alike to be able to identify quartz, recognize it in its various forms and understand its characteristics. Consisting of the elements silicon and oxygen (a combination called silica), quartz is generally colorless to white when very pure, but even small amounts of impurities can tint quartz any color. Well-formed quartz crystals are hexagonal (six-sided) and tipped with a point. Also known as “rock crystals,” these glassy crystals are common and frequently found within cavities in rocks. Particularly thin and steep crystals are called needle quartz, a name that reflects their shape. Although quartz crystals are not rare, they are not as common as quartz’s many other forms. Water-worn quartz pebbles are often found in rivers, while white quartz veins extend through rocks, and massive quartz fragments are strewn upon mountain roadsides. The most common quartz specimens are white or gray grains and masses in granite and other coarse-grained rocks. Identification of quartz is easy when you note its abundance, high hardness, six-sided crystal shape, and conchoidal fracture (when struck, circular cracks appear). It also produces a spark when chipped.

Where to Look: Quartz can be found virtually anywhere in Colorado, but particularly in the central portions of the state.