the sand

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Sand
Sand
Sand
Sand
Sand
Sandals
Sandals
Sandals
Sandal
Sandal
Sandwich
Sandcastle
Sandcastle
Sandcastle
Sandman
Sandcastle
Sandcastle
Sandcastle
Sandwich
Sandwich
Sandal
Sandwich
Sandwich
Sandal
Sandwich
Sandwich
Sandals
Sandcastle
Sandcastle
Sandwich
Sandwich
Sandwich

Sand is a granular material composed of finely divided rock and mineral particles. Sand has various compositions but is defined by its grain size. Sand grains are smaller than gravel and coarser than silt. Sand can also refer to a textural class of soil or soil type; i.e., a soil containing more than 85 percent sand-sized particles by mass.

The composition of sand varies, depending on the local rock sources and conditions, but the most common constituent of sand in inland continental settings and non-tropical coastal settings is silica (silicon dioxide, or SiO2), usually in the form of quartz.

Calcium carbonate is the second most common type of sand, for example, aragonite, which has mostly been created, over the past 500 million years, by various forms of life, like coral and shellfish. For example, it is the primary form of sand apparent in areas where reefs have dominated the ecosystem for millions of years like the Caribbean. Somewhat more rarely, sand may be composed of calcium sulfate, such as gypsum and selenite, as is found in places like White Sands National Park and Salt Plains National Wildlife Refuge in the U.S.

Sand is a non-renewable resource over human timescales, and sand suitable for making concrete is in high demand. Desert sand, although plentiful, is not suitable for concrete. 50 billion tons of beach sand and fossil sand is used each year for construction.

Vocabulary

the toasted sandwich
das getoastete Schinken-Käse-Sandwich
the sand
der Sand
the sandals
die Sandalen
les sandales
the sandwich
thousand
thousands of
des milliers de