Curtis, Neville J. <br/><br/>
A review of the classification of opal with reference to recent new localities 

 - Basel  MDPI  May 2019 
 - 20 p. 
<br/><br/><label>ISSN: </label>2075-163X 
<br/><br/><label>Subjects--Topical Terms: </label><br/>OPALO<br/>CLASIFICACION<br/>GEMAS
<br/><br/><label>Subjects--Geographic Terms: </label><br/>MADAGASCAR<br/>PERU<br/>TANZANIA