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The name is from the Spanish word placer, meaning "alluvial sand". Placer mining is an important source of gold, and was the main technique used in the early years of many gold rushes, including the California Gold Rush. Types of placer deposits include alluvium, eluvium, beach placers, aeolian placers and paleo-placers. [2]
Placer mining is frequently used for precious metal deposits (particularly gold) and gemstones, both of which are often found in alluvial deposits—deposits of sand and gravel in modern or ancient stream beds, or occasionally glacial deposits. The metal or gemstones, having been moved by stream flow from an original source such as a vein, are ...
All of the plants Lewis collected in the first months of the Expedition were cached near the Missouri River to be retrieved on the return journey. The cache was completely destroyed by Missouri flood waters. Other collections were lost in varying ways, and we now have only 237 plants Lewis collected, 226 of which are in the Philadelphia ...
List of elm species; List of Encyclia species; List of Epidendrum species; List of Eragrostis species; List of Eremophila (plant) species; List of Erica species; List of Erigeron species; List of Eryngium species; List of Erysimum species; List of Eucalyptus species; List of Eugenia species; List of Eulophia species; List of Euonymus species ...
"Panning out" ~ Stereoscopic view of print taken by the U.S. Geological and Geographic Survey of the Territories ~ circa 1874–1879 Gold panning is a simple process. Once a suitable placer deposit is located, some alluvial deposits are scooped into a pan, where they are then wetted and loosed from attached soils by soaking, fingering, and aggressive agitation in water.
The list includes individual plant species identified by their common names as well as larger formal and informal botanical categories which include at least some domesticated individuals. Plants in this list are grouped by the original or primary purpose for which they were domesticated, and subsequently by botanical or culinary categories.
Plants of the World: An Illustrated Encyclopedia of Vascular Plants. Chicago, Illinois: Kew Publishing and The University of Chicago Press. ISBN 978-0-226-52292-0. Coombes, Allen (2012). The A to Z of Plant Names: A Quick Reference Guide to 4000 Garden Plants. Portland, Oregon: Timber Press. ISBN 978-1-60469-196-2. Cullen, Katherine E. (2006).
The most common species of the group is monazite-(Ce), that is, the cerium-dominant member of the group. [4] It occurs usually in small isolated crystals . It has a hardness of 5.0 to 5.5 on the Mohs scale of mineral hardness and is relatively dense , about 4.6 to 5.7 g/cm 3 .