User:Stone/Fluoride

Elemental potassium does not occur in nature because it reacts violently with water (see section Precautions below). As various compounds, potassium makes up about 2.6% of the weight of the Earth's crust and is the seventh most abundant element, similar in abundance to sodium at 2.8% of the crust.{{cite book | url =http://books.google.de/books?id=iXfhFnoQBQ0C&pg=PA80 }} In seawater, potassium at 0.39 g/L (0.039 wt/v %) is far less abundant than sodium at 10.8 g/L (1.08 wt/v %).{{cite book | url = http://books.google.de/books?id=NXEmcGHScV8C&pg=PA3 }}{{cite book | url = http://books.google.com/books?id=zNicdkuulE4C&pg=PA723 }}

Orthoclase (potassium feldspar) is a common rockforming mineral. Granite for example contains 5% potassium which is well above the average in the Earth's crust. Some minerals with a very high potassium contain are for example niter, sylvite, carnallite, kainite and langbeinite. All of those minerals are used to produce potassium compounds.

Salt]], NaFe₄S₃(CO)₇