The most common imitation of turquoise encountered today is dyed howlite and magnesite, both white in their natural states, and the former also having natural ( and convincing ) black veining similar to that of turquoise.
12.
Some destructive tests may, however, be necessary; for example, the application of diluted hydrochloric acid will cause the carbonates odontolite and magnesite to effervesce and howlite to turn green, while a heated probe may give rise to the pungent smell so indicative of plastic.
