194 -MGotois’ 
from the chemical nature, of an earthy mineral, in an amorphous state, 
being insufficient to ascertain, decisively, to what speciesit corresponds, 
P remaitied long uncertain of the nature of this mineral’ till, at length, 
some crystals of well characterised épidote, found in a ‘small cavity of 
a vein of this substance, dispelled all my doubts on the subject.” ‘Soon 
afterward, an attentive examination of several amphiboloids demon- 
strated to me, that they admitted in their composition, epidote, some- 
times even in a great proportion. This observation’ justifies the im- 
portance attributed, by Haiiy, to the character of the crystalline form. 
From the concurrence of epidote; among the other elements of 
amphiboloid, originates a rock, of a fine dark ereen colour, susceptible 
ofa good polish, and which, at first sight, may be confounded with 
some variety of serpentine, “When the gee are so entwined to- 
gether, as to present a ‘colour almost uniform, it” may, be considered 
as analogous to the rock, called Egyptian basalt by antiquaries, which 
was employed by the ancients in making figures and busts, several of 
which are seen in collections of the antiquities of Italy. -~But, com- 
monly it consists of small acicular crystals of amphibole, imbedded in 
a kind of cement, composed of felspar and epidote. Some specimens 
present those three substances in distinct and separaté state, like the 
elements of the granite. 
This rock, which I denote by the name of epidotic amphiboloid, 
does not form so extensive masses, as the preceding species. ~ It is 
found contiguous to felspar [Brighton]; or in the form of veins, 
running across a porphyritic wacke [Brighton 4, Dedham turnpike]. 
ft, almost always, includ tic sulphurated iron, often crystallised 
in small striated cubes fRoxbury OL ne appearing constantly sensi- 
ble tothe magnet. “It is of great tenacity, with a rough fracture. It 
falls mto polyedrons, which sometimes present a prismatic shape. 
— of this rock, exposed at the surface of the earth, seem more 
