Examine the specimen for structural integrity, ensuring that crystals are firmly attached to the matrix and that there are no signs of advanced deterioration. Some surface oxidation creating colorful iridescence is desirable, but excessive flaking or crumbling indicates instability.
The source location can also be significant, as pyrite from different regions often displays unique characteristics. Spanish pyrite is renowned for perfect cubic crystals, Peruvian specimens often feature impressive clusters, and Chinese pyrite frequently displays intricate crystal combinations. Large specimens from any reputable source carry similar metaphysical properties, though some practitioners develop preferences based on personal experience.