Kidney stones are made up of various minerals and salts that crystallize in the urine. The most common types of kidney stones and their chemical compositions are:

1. Calcium Oxalate Stones (75-80% of stones):

* Calcium Oxalate Monohydrate (Whewellite): CaC₂O₄·H₂O

* Calcium Oxalate Dihydrate (Weddellite): CaC₂O₄·2H₂O

2. Calcium Phosphate Stones (10-15% of stones):

* Hydroxyapatite: Ca₅(PO₄)₃OH

* Brushite: CaHPO₄·2H₂O

3. Struvite Stones (10-15% of stones):

* Struvite: MgNH₄PO₄·6H₂O

* Newberyite: MgHPO₄·3H₂O

4. Uric Acid Stones (5-10% of stones):

* Uric acid: C₅H₄N₄O₃

5. Cystine Stones (1-2% of stones):

* Cystine: C₆H₁₂N₂O₄S₂

Other rarer types:

* Xanthin Stones: C₅H₄N₄O₂

* 2,8-Dihydroxyadenine Stones: C₅H₅N₅O₃

The specific composition of a kidney stone can vary depending on individual factors such as diet, genetics, and medical conditions. However, the majority of kidney stones are composed of calcium oxalate, calcium phosphate, or a combination of both.