Placer

Placer may refer to one of the following:

Geographical names:

Placer deposit

In geology, a placer deposit or placer is an accumulation of valuable minerals formed by gravity separation during sedimentary processes. 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, and paleoplacers.

Placer materials must be both dense and resistant to weathering processes. To accumulate in placers, mineral particles must be significantly denser than quartz (whose specific gravity is 2.65), as quartz is usually the largest component of sand or gravel. Placer environments typically contain black sand, a conspicuous shiny black mixture of iron oxides, mostly magnetite with variable amounts of ilmenite and hematite. Valuable mineral components often occurring with black sands are monazite, rutile, zircon, chromite, wolframite, and cassiterite.

Glossary of rugby league terms

This list of rugby league terms is a general glossary of the terminology used in the sport of rugby league football. The sport has accrued a considerable amount of jargon to describe aspects of the game. Many terms originate from the Laws of the Game. A number of aspects of the game have more than one term that refers to them. Different terms have become popularly used to describe an aspect of the game in different places with notable differences between the northern and southern hemispheres.

Where words in a sentence are also defined elsewhere in this article, they appear in italics.

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If the ball enters touch, then play is restarted by a scrum at the point where the ball left the field of play. However, if the ball is kicked into touch without first bouncing inside the field of play (on the full). In this case, the scrum is taken from level with the place from where the ball was kicked from. The ball is given back to the team who did not kick it out of bounds; ball back is waived in certain circumstances: