Question: is opal the same as pearl?
Answer: The main difference between Opal and Pearl is that the Opal is a silica mineral and Pearl is a hard object produced within the soft tissue of a living shelled mollusc. Opal is a hydrated amorphous form of silica (SiO2·nH2O); its water content may range from 3 to 21% by weight, but is usually between 6 and 10%.