Page 29 - Curriculum Visions Dynamic Book

For more on magnesium, see Volume 3: Calcium and Magnesium in the Elements set.
Geology
Magnesium is common in sea water and in evaporite deposits (dried ancient lake beds). Dolomite, a form of limestone, is MgCa(CO3)2.
Biology
Magnesium is also important in living things. In plants the green pigment chlorophyll is a compound of magnesium. Magnesium is needed in animals to make some enzymes work. People need about 0.3g of magnesium each day.
Compounds of magnesium include those used in medicine, such as Epsom salts (magnesium sulphate, MgSO4) and milk of magnesia (magnesium carbonate, MgCO2).
Epsom salts were named after Epsom, south of London, England, where the magnesium mineral was first discovered
in well water. Magnesium salts make the water taste bitter.
Magnesium salts are not harmful to health.
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 A piece of dolomite.This hard rock, which contains magnesium carbonate, produces sharp peaks and dramatic scenery that is characteristic of the Dolomites, a mountain range in the southern Alps of northeastern Italy.