At Cerro de Mercado numerous veins containing gemmy, lemon yellow to greenish fluorapatite crystals cut through the hematite massif. These crystals have been collected for decades from the iron mines in Cerro de Mercado, but they have become much more scarce with recent mechanization of the mining operations. The bright, lustrous crystals form hexagonal shapes with off-center terminations. They are found in vugs, often associated with quartz and calcite. Most crystals are around an inch in length, though larger crystals up to about 4 inches long have been found.