The correct option is HgS.
Explanation
Cinnabar is a toxic mercury sulfide mineral with a bright scarlet to brick-red color. It serves as the primary ore for the extraction of elemental mercury.
Analysis of Options:
- HgS HgS (Correct): This is the chemical formula for Cinnabar (Mercury(II) sulfide). Upon heating in air (roasting), it converts to mercury oxide, which is then reduced to mercury.
- Cu2S Cu2S (Incorrect): This is the formula for Chalcocite, which is an important ore of copper.
- ZnS ZnS (Incorrect): This represents Zinc Blende (Sphalerite), which is the principal ore of zinc.
- FeS FeS (Incorrect): This represents Iron(II) sulfide. Common iron ores include Hematite (Fe2O3) and Magnetite (Fe3O4).
Key Takeaway: Cinnabar is the sulfide ore of Mercury, chemically represented as HgS.