Prezioso e raro esemplare non trattato di opale etiope di Wello di grande bellezza, con meravigliosi giochi di colore e sfumature accentuate dalle fratture interne. Importante pezzo da collezione stabile, eccezionale alla luce del sole. Fotografato perfettamente asciutto. ___________________________________________________________ An opal is a hydrated form of silica with a water content ranging from 3 to 21%.Indeed, it is this permeability to water that makes it a hydrophile. Opals are deposited at a relatively low temperature and may occur in the fissures of almost any kind of rock, being most commonly found with limonite, sandstone, rhyolite, marl, and basalt. Only precious opals show a variable interplay of internal colors. At microscopic scales, precious opal is composed of silica spheres some 150 to 300 nm in diameter in a hexagonal or cubic close-packed lattice. These ordered silica spheres produce the internal colors by causing the interference and diffraction of light passing through the microstructure of the opal.