The Death Valley region is one of the hottest places in the United
States. Can you image that millions of years ago, there was an ocean of
water that covered this area. Slowly, as plate tectonics started to
create nearby mountains, salt water became trapped and evaporate. During
the Pleistocene, lakes filled these area that were concentrated with borate
components. These compounds would later become one of the richest
sources of borate (B2O3) minerals in the world.
Most borate minerals are found in a type of sedimentary
rock that is called an evaporite which is formed by precipitation.
Precipitation is the growth of crystals from a water solution.
Evaporites form in many places, especially within lakes in desert areas.
The removal of water, concentrates the dissolved elements in the water.
In the case of borate minerals, the water contains dissolved sodium,
calcium, and B2O3.
Searless Lake, California