Abstract
The present relations among the hydrated sodium borate minerals at the Kramer deposit at Boron, California, when considered in the light of laboratory results on vapor pressure measurements and solubility polytherms of the Na 2 B 4 O 7 -H 2 O system, and of the crystal structure of borax and the colemanite series of minerals, show that the ore body was originally deposited as a chemical precipitate of borax from a saline lake at 25 degrees -35 degrees C. and that conversion of borax to kernite took place on burial to a depth on the order of 2,500 ft. and in the temperature range 53 degrees -63 degrees C. Crystal chemical considerations provide an adequate explanation of some of the apparently anomalous and puzzling features of the experimental physical chemical results previously found for the Na 2 B 4 O 7 -H 2 O system, and indicate that the formulas for borax, tincalconite, and kernite are correctly written as Na 2 B 4 O 5 (OH) 4 .8H 2 O, Na 2 B 4 O 5 (OH) 4 .3H 2 O, and Na 2 B 4 O 6 (OH) 2 .3H 2 O, respectively.
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