OCCURRENCE OF OPAL NEAR NE\V ROSS, N. S. — PIERS. 447 



The specimen is the Girasol variety of Opal, which is 

 defined by Dana as ''blnish-white, translucent, with reddish 

 reflections in a bright light." More play of colours or fire-like 

 reflections would make it a Preciou^ or a Fire-opal; and a 

 lack of such colour, a Common Opal. 



The specimen furnishes the following description: Its 

 greatest length is .35 of an inch; and its thickness about .22 

 of an inch. The original weight was 40.9 centigrammes. 

 Hardness about 6. Specific gravity, 2.12 (Opal has a specific 

 gravity varying from 1.9 to 2.3; but when pure, from 2.1 to 

 2.2; being thus less than quartz, which is from 2.5 to 2.8), 

 The lustre is vitreous or subvitreous. Colour milk-white, with 

 rather feeble internal reflections or glows of a delicate 

 vinaceous-pink (jDale yellowish pink) colour, Avhen turned 

 about in a strong light. Streak white. In diaphaneity it is 

 subtransparent. 



It is soluble, when powdered, in strong, hot potassium 

 hydroxide; gives off water when heated in the closed tube; is 

 infusible before the blowpipe; and is readily scratched by 

 quartz (7) and scratches apatite (5). These characteristics 

 and its low specific gravity plainly show that it is not any of 

 the varieties of ordinary quartz. 



Mr. Keddy writes me (18th May, 1910) that he has a 

 smaller specimen which is much handsomer, having more play 

 of colours, red, yellow and blue ; and if this is so, it must more 

 nearly approach the Precious Opal. 



With these handsomer specimens, he says, there were found 

 others, reddish-broT\Ti and yellow, and opaque; all occurring 

 in the same quartz vein. The Museum received from him 

 on 19th J^ovember, 1910, two of these latter duller specimens 

 (accession no. 3661). They consist of Common Opal (milky 

 white) in what is doubtless Jasp-opal (brownish yellow). One 

 of these two sj3ecimens weighs 21.1 centigrammes and is of a 

 cinnamon (bro^^^lish yellow) colour and opaque; with milk- 



