 Occurrence
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| In 2005, China was the top producer of strontium with almost two-thirds world share followed by Spain and Mexico, reports the British Geological Survey.
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| Strontium commonly occurs in nature, the 15th most abundant element on earth, averaging 0.034% of all igneous rock and is
found chiefly as the form of the sulfate mineral celestite (SrSO4) and the carbonate strontianite (SrCO3). Of the two, celestite occurs much more frequently in sedimentary deposits of sufficient size to make development of mining
facilities attractive. Strontianite would be the more useful of the two common minerals because strontium is used most often
in the carbonate form, but few deposits have been discovered that are suitable for development. The metal can be prepared
by electrolysis of melted strontium chloride mixed with potassium chloride:
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Sr2+ + 2e-  Sr
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| 2Cl- Cl2(g) + 2e- |
| Alternatively it is made by reducing strontium oxide with aluminium in a vacuum at a temperature at which strontium distills off. Three allotropes of the metal exist, with transition points at 235 and 540°C. The largest commercially exploited deposits are found in England.
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