Calcium Phosphate crystals typically appear as thin, wedge-like rods with variable birefringence

These rods can also form in star-like clusters with variable birefringence.

The crystals may also appear as large, irregular plates that may form a scum on the surface of sitting urine. These plates show no birefringence.

Bilirubin crystals can look similar to calcium phosphate rosettes when they form in clusters. However, bilirubin crystals are easily identified by the presence of bilirubin which typically stains other elements. They are also found in acidic, not alkaline urine.

Tyrosine crystals form in both needles and clusters. However, tyrosine needles are much more fine than the wedge-like calcium phosphate. Tyrosine crystals are sometimes described as “hair-like.”