Question

Identify the ores of magnesium metal?
A. Carnallite
B. Magnesite
C. Dolomite
D. All of these

Answer 1

Magnesium is obtained from its ore. Magnesium ores are used commercially and magnesium metal can be extracted by electrolysis or by the process of thermal reduction. Magnesium and its compounds are used in many works such as insulation, alloy formation, agriculture, fertilizers, aerospace and other industries.

Complete step by step answer:
Let us discuss the options one-by-one to find the ores of magnesium:
A. Carnallite: Carnallite also known as Carnallite. It is an evaporite mineral. It is a hydrated chloride of potassium and magnesium, with chemical formula $\text{KMgC}{{\text{l}}_{3}}.6\left( {{\text{H}}_{2}}\text{O} \right)$. It is deliquescent. It forms under specific environment conditions. It exists in various colours red, yellow, white and blue.
B. Magnesite: The ore is formed by the alteration of carbonate rocks or magnesium-rich rocks by chemical weathering or metamorphism. The ore is named after the presence of magnesium in this ore and its composition. This is the mineral of carbonate of magnesium which has a chemical formula $\text{MgC}{{\text{O}}_{3}}$. It contains 28.8% of magnesium in it. It is a white gemstone.
C. Dolomite: Dolomite rock type is also known as dolostone. The term dolomite is also used for sedimentary carbonate rock which is mostly composed of dolomite. It is an anhydrous carbonate mineral which contains calcium magnesium carbonate, with chemical formula $\text{CaMg}{{\left( \text{C}{{\text{O}}_{3}} \right)}_{2}}$. It contains 18.2% of magnesium in it. It exists in various colours like white, gray and pink. Dolomite is related to huntite $\left[ \text{M}{{\text{g}}_{3}}\text{Ca}{{\left( \text{C}{{\text{O}}_{3}} \right)}_{4}} \right]$.
Carnallite, Magnesite and Dolomite are the ores of magnesium metal, which is option ‘(d)’.

Additional Information: The other ores of magnesium are brucite, $\text{Mg}{{\left( \text{OH} \right)}_{2}}$, which contains 41.7% of magnesium, bischofite, $\text{MgC}{{\text{l}}_{2}}.6{{\text{H}}_{2}}\text{O}$, containing 12% of magnesium, kieserite, $\text{MgS}{{\text{O}}_{4}}.{{\text{H}}_{2}}\text{O}$, containing 17.6% of magnesium, langbeinite, $2\text{MgS}{{\text{O}}_{4}}$.

Note: To obtain the magnesium, calcium hydroxide $\left[ \text{Ca}{{\left( \text{OH} \right)}_{2}} \right]$ is added to sea water to form precipitate of magnesium hydroxide. Brucite is insoluble in water which can be filtered, which then, reacts with hydrochloric acid $\left( \text{HCl} \right)$ to produce concentrated magnesium chloride $\left( \text{MgC}{{\text{l}}_{2}} \right)$. By the electrolysis of magnesium chloride, magnesium is produced.