Here's why:
* Sulfate anion: The defining characteristic of sulfate minerals is the presence of the sulfate anion (SO₄²⁻). This anion is a negatively charged group made of one sulfur atom and four oxygen atoms.
* Cations: The sulfate anion will then bond with positively charged ions (cations) to form a neutral compound. These cations can be various elements, including but not limited to:
* Calcium (Ca) in gypsum (CaSO₄·2H₂O)
* Barium (Ba) in barite (BaSO₄)
* Magnesium (Mg) in kieserite (MgSO₄·H₂O)
* Sodium (Na) in thenardite (Na₂SO₄)
* Potassium (K) in aphthitalite (K₂SO₄)
Therefore, while every sulfate mineral contains sulfur and oxygen, the specific chemical formula and additional elements will vary depending on the cation involved.
