Most Important Ores & Chemical Formulas
Memorizing the chemical formulas of principal ores is non-negotiable for JEE and NEET. Every year, at least one 4-mark question directly tests formula matching or asks you to identify the primary ore of a specific metal. This guide categorizes the most heavily tested ores into Oxides, Sulphides, Carbonates, Halides, and Sulphates for maximum retention.
Chemca Visual: Major Ore Classifications
1. Oxide Ores
Oxide ores are incredibly common for highly reactive metals and transition metals. They are typically concentrated using gravity separation or magnetic separation (if magnetic).
| Ore Name | Principal Metal | Chemical Formula |
|---|---|---|
| Bauxite | Aluminium (Al) | Al2O3 · xH2O |
| Haematite | Iron (Fe) | Fe2O3 |
| Magnetite | Iron (Fe) | Fe3O4 |
| Cuprite (Ruby Copper) | Copper (Cu) | Cu2O |
| Zincite | Zinc (Zn) | ZnO |
| Cassiterite (Tin Stone) | Tin (Sn) | SnO2 |
| Rutile | Titanium (Ti) | TiO2 |
2. Sulphide Ores
Sulphide ores are heavily tested because they require specific concentration methods (Froth Floatation) and roasting before reduction.
| Ore Name | Principal Metal | Chemical Formula |
|---|---|---|
| Zinc Blende (Sphalerite) | Zinc (Zn) | ZnS |
| Galena | Lead (Pb) | PbS |
| Cinnabar | Mercury (Hg) | HgS |
| Copper Pyrites (Chalcopyrite) | Copper (Cu) | CuFeS2 |
| Copper Glance (Chalcocite) | Copper (Cu) | Cu2S |
| Iron Pyrites (Fool's Gold) | Iron (Fe) | FeS2 |
⚠️ Chemca JEE Trap: Copper Pyrites vs. Iron Pyrites
Do not confuse Copper Pyrites (CuFeS2) with Iron Pyrites (FeS2). Though Iron Pyrites contains iron, it is rarely used to extract iron due to its high sulphur content causing brittleness (it's primarily used to manufacture H2SO4). Copper Pyrites, however, is the primary ore for extracting Copper.
3. Carbonate Ores
Carbonate ores undergo Calcination (heating in the absence of air) to convert them into metallic oxides before reduction.
| Ore Name | Principal Metal | Chemical Formula |
|---|---|---|
| Siderite | Iron (Fe) | FeCO3 |
| Calamine | Zinc (Zn) | ZnCO3 |
| Malachite | Copper (Cu) | CuCO3 · Cu(OH)2 |
| Azurite | Copper (Cu) | 2CuCO3 · Cu(OH)2 |
| Limestone / Marble | Calcium (Ca) | CaCO3 |
| Dolomite | Ca and Mg | CaCO3 · MgCO3 |
Chemca Visual: The Malachite vs. Azurite Trap
4. Halide Ores
| Ore Name | Principal Metal | Chemical Formula |
|---|---|---|
| Rock Salt | Sodium (Na) | NaCl |
| Sylvine | Potassium (K) | KCl |
| Horn Silver | Silver (Ag) | AgCl |
| Carnallite | Mg and K | KCl · MgCl2 · 6H2O |
| Cryolite | Aluminium (Al) | Na3AlF6 |
| Fluorspar | Calcium (Ca) | CaF2 |
💡 Chemca Pro-Tip: Complex Formulas
Cryolite (Na3AlF6) is heavily tested in the metallurgy of Aluminium (Hall-Heroult process), not just as an ore, but as a solvent added to Alumina to lower its melting point and increase conductivity. Carnallite is a classic double salt tested frequently in Coordination Compounds as well.
5. Sulphate Ores
| Ore Name | Principal Metal | Chemical Formula |
|---|---|---|
| Gypsum | Calcium (Ca) | CaSO4 · 2H2O |
| Epsom Salt | Magnesium (Mg) | MgSO4 · 7H2O |
| Anglesite | Lead (Pb) | PbSO4 |
| Barytes | Barium (Ba) | BaSO4 |
Chemca 15-Question Rapid Recall Quiz
Cover the tables above and test your memory. This is the exact pattern of JEE Match-the-Following questions.
Q1. What is the chemical formula of Calamine?
Q2. Distinguish the formulas of Malachite and Azurite.
Q3. Which metal is extracted from Cassiterite?
Q4. Write the formula for Carnallite.
Q5. Sphalerite is an ore of which metal, and what is its chemical composition?
Q6. Name a double carbonate ore of Calcium and Magnesium.
Q7. What is the common name for FeS₂?
Q8. Which halide ore is essential in the Hall-Heroult process for extracting Aluminium?
Q9. Differentiate between Haematite and Magnetite formulas.
Q10. Anglesite is an ore of which heavy metal?
Q11. Cuprite is also known by what common name due to its color?
Q12. Write the formula of Epsom salt.
Q13. Name the principal sulphide ore of lead.
Q14. What is the chemical name and formula of Horn Silver?
Q15. Why is Bauxite considered an ore of Al, but clay is only a mineral?
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