Wikipedia: Magnesium

Like its lower periodic table group neighbor calcium, magnesium reacts with water at room temperature, though it reacts much more slowly than calcium.

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Too much magnesium in the [diet] may make it difficult for the body to absorb calcium.

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Both of these alloys are recent developments in high temperature low creep magnesium alloys. The general strategy for such alloys is to form intermetallic precipitates at the grain boundaries, for example by adding mischmetal or calcium.

Calcium

Uses include: as an alloying agent used in the production of aluminium, beryllium, copper, lead, and magnesium alloys.

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[Humphry Davy] worked with electrolysis throughout his life and also discovered/isolated magnesium, strontium and barium.

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Calcium carbonate is the most common and least expensive calcium supplement. It can be difficult to digest and causes gas in some people. Taking magnesium with it can help to prevent constipation.

If you were Russian you would have more respect for the power of Mendeleyev's periodic table.

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