1824.] Mr. W. Phillips on Cleavelandite. 119 



sion from the porphyry or el van dykes of Cornwall ; the imbed- 

 ded crystals being all felspar. 



This mineral appears to be the only substance connected with 

 hypersthene, in the hypersthene rock of Sky, for I have not been 

 able to detect any felspar in the several specimens of that rock 

 presented to me by L)r. Mac Culloch. I have detected it in 

 contact with felspar in some fragments of granites from Tiree, 

 presented to me for the purpose of examination by Capt. Vetch, 

 as were also others from the Shetland Isles, Fula and Faira, in 

 which also the cleavelandite occurs. To the same gentleman 1 

 am likewise indebted for a mass consisting of nearly white 

 lamellar felspar and green cleavelandite in about equal propor- 

 tions, simply adhering, not intermixed; as well as for an isolated 

 fragment about an inch and a half square, of the latter mineral Of 

 a dark colour, having greatly the aspect of felspar, its cleavage 

 planes being more than usually bright. Both these specimens 

 are from Tiree. 



The presentation to me of a box of rock specimens from 

 Mont Blanc and its neighbourhood, by Charles Hampden Tur- 

 ner, Esq. with a catalogue " fourni par Joseph Marie Des- 

 champs, a Servoz, Canton de Chamouni," afforded a favourable 

 opportunity for their examination, especially as a large part of 

 them, indeed all in which I found the cleavelandite, are noted 

 in the catalogue as the " protogine granites of Jurine." In the 

 specimen of the very summit rock of Mont Blanc, cleavelandite 

 forms a considerable proportion, in connexion with steatite, talc, 

 quartz, chlorite, and felspar ; the cleavelandite being white, 

 nearly opaque, and often considerably granular : it occurs even 

 still more largely in the beautiful porphyritic granite ofPormenaz 

 about two miles W or NVV of Servoz, and in which the imbedded 

 substance is a felspar of a delicate rose colour ; the paste con- 

 sists of cleavelandite, quartz, felspar, hornblende, and chlorite, 

 and the aggregate is of a green colour. The rock of Vosa con- 

 sists of dark lamellar felspar, imbedded chiefly in yellow and 

 white cleavelandite including yellow mica. That of La Filla 

 consists of nearly white and opaque cleavelandite, mica, chlo- 

 rite, quartz, and felspar, and that of Brevent of the same sub- 

 stances. The rock of Des Trapettes consists chiefly of white 

 cleavelandite and white mica (it is elastic), containing spots of 

 yellow mica ; neither quartz nor chlorite is perceptible in it ; 

 and much of the cleavelandite has a granular aspect when 

 viewed in a direction contrary to that of the cleavage planes ; 

 two surfaces of this specimen are, however, coated by chlorite. 



The only specimen of a rock in my possession from North 

 America, is one consisting chiefly of black mica, with which 

 transparent cleavelandite is intermixed ; garnets are imbedded 

 in it : this rock is from the banks of the Schuylkill, five miles W 

 of Philadelphia. 



