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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 ...
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.
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 ...
Of more than 50,000 edible plant species in the world, only a few hundred contribute significantly to human food supplies. Just 15 crop plants provide 90 percent of the world's food energy intake (exclusive of meat), with rice, maize and wheat comprising two-thirds of human food consumption. These three alone are the staples of over 4 billion ...
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 .
Many animals regularly visit mineral licks to consume clay, supplementing their diet with nutrients and minerals. In tropical bats, lick visitation is associated with a diet based on wild figs ( Ficus ), which have very low levels of sodium, [ 3 ] [ 4 ] and licks are mostly used by females that are pregnant or lactating.
The plants listed may be ornamental, medicinal, and/or edible. Several of them bear edible fruit. Plants are selectively bred for phenotypic traits (such as flower colour) and other hereditary traits. When developing a new variety, a plant breeder might value such characteristics as appearance, disease resistance, and hardiness.