266 



Mr. Brooke un Zoizite. 



celli, who has published a work in iUiistration of the minerals 

 found in the neighbourhood of that mountain. The general 

 aspect of the crystals is that of quartz, and might by a cur- 

 sory observer be mistaken for it. The colour generally is 

 yellowish, but there are some crystals nearly colourless and 

 nearly transparent; and on placing a portion of the specimen 

 in dilute muriatic acid to dissolve the carbonate of lime, I 

 found that the surfaces of the yellowish crystals becan^e dull, 

 and were covered with a yellowish powder, leaving the crystals 

 less coloured than they were at first. 



The primary form is a right rhombic prism of about 132° 54 , 

 a terminal edge being to a lateral edge as 1 to 1-046 very 



I have not observed any cleavage planes on the fractured 

 surfaces, and the crystals are too small to allow of much other 

 examination in this respect. The hardness is between that of 

 apatite and felspar. There is no crystal sufficiently free from 

 the matrix to allow of the specific gravity being ascertained; 

 nor are the surfaces of the crystals sufficiently perfect to affiard 

 very accurate measurements. The following therefore may 

 admit of some slight correction: 



Planes e, c, h. 



1 

 B, 



E, 



1 

 G. 



Symbols 



M,M'= 132° 54' 

 M,6' = 145 00 



e,^ = 141 48 



h,c = 138 46 

 M,h =113 33 



Zoizite. 



This mineral has been confounded with Epidote by Haiiy, 

 probably from the occurrence of crystals of that substance in 

 the Zoizite of Hoff ; and in this mistake he has been followed 

 bv most other writers on the subject. 



" The late W. Phillips says, " it cleaves parallel to the planes 

 of a right rhombic prism of about 60° and 120°." 



Mr. Haidinger, in his Treatise on Mineralogy, says that 

 Epidote and Zoizite are easily distinguished by their colours. 

 And in reference to the angle which I had given as that of 

 Zoizite, differing from the angle of Epidote, he says ; " this 

 would render it necessary to consider Zoizite as a particular 

 species." Hence it is clear that Mr. Haidinger could not 

 have examined this mineral; for if he had, he must immediately 

 have perceived its difference from Epidote. 



J. have lately obtained a small crystal of Zoizite with terminal 



planes, 



