M. Godon’s mineralogical observations. ~ 135 
forcibly to -resist decomposition, than most of the other species of 
amphiboloid. 
Epidotic amphiboloid is Sapentible of admitting crystals of felspar, 
and thus becoming porphyritic. Such are some fragments, found in 
loose pieces, particularly on the Blue Hills. This remarkable varie- 
ty presents crystals. of white felspar, sometimes of an inch in one di- 
mension, accompanied by cubic sulphurated iron, and globules of la- 
minary carbonated Jime of a perfect transparency ; the diameter of 
these. globules not exceeding three-or four lines. 
- By comparing the green antique porphyry, with a variety of por- 
phyritic amphiboloid, found in this country, and which includes epi- 
dote, Iam ind sider this rock, the locality of which is un- 
ANNs es 
known to the meders, 2 as also admitting epidote in its composition, 
and, probably, as receiving its fine colour from. this substance. | I 
place this. variety, which I have not observed in place, near the porph- 
yritic.amphiboloid, with the designation of ophites. 
nas Somesimes, PS: sis 5 quartz in its composition, 
artzose a id) and ne formed entirely of amphi- 
pole and aonree. This rock is ‘dscnraied ee some light veins of 
quartz, by a fracture somewhat conchoidal, and by its resisting,.more 
than any other, spontifheous decomposition [Menotomy QO]. When 
these elements exist in fine mixture, so as to present as it were anho- 
ae 
mogencous paste, it is hardly possible to distinguish it from trappine 
ampliboloid when tound in insulated pieces [Roxbury 9, Brighton 
O]- Both these rocks, when conveniently cut and smoothed, may be 
used as touch-stone. 
11. I give the name micaceous to the gsuphabeil including mica. 
This last mineral appears not uniformly distributed, but accidentally 
disseminated in some parts of common and granitic amphiboloid 
EMenotomy ©, Concord turnpike ]. Its most usual colour is the 
