Why stone is formed in the kidney?

Nephrolithiasis. There are many different types of stones including calcium oxalate (mono & dihydrate), calcium phosphate, struvite, cystine, indinvir, matrix and uric acid stones, to name a few. However, the types of stone is not the whole answer. A complete stone risk analysis also includes specific serum and urine studies. In general, stone for from concentrated urine leading to crystallization then to stones.