Which one of the following materials contains calcium?

Q. Which one of the following materials contains calcium?

1. China clay
2. Gypsum
3. Corundum
4. Talc

Answer: Gypsum

• Kaolinite is a clay mineral, part of the group of industrial minerals with the chemical composition Al₂Si₂O₅(OH)₄. It is a layered silicate mineral, with one tetrahedral sheet of silica linked through oxygen atoms to one octahedral sheet of alumina octahedra.
• Gypsum is a soft sulfate mineral composed of calcium sulfate dihydrate, with the chemical formula CaSO₄·2H₂O. It is widely mined and is used as a fertilizer and as the main constituent in many forms of plaster, blackboard/sidewalk chalk, and drywall.
• Corundum is a crystalline form of aluminum oxide typically containing traces of iron, titanium, vanadium, and chromium. It is a rock-forming mineral. It is also a naturally transparent material but can have different colors depending on the presence of transition metal impurities in its crystalline structure
• Talc is a clay mineral composed of hydrated magnesium silicate with the chemical formula Mg₃Si₄O₁₀(OH)₂. Talc in powdered form, often in combination with corn starch, is widely used as baby powder.