CRYSTALLISED GADOLINITE. 349 
sabanbsek Gravity, 3.4802. The {pecimen iat 1136.39 
~ «grains. Its furface is a little decompofed, and it has allo 
fome minute particles of telfpar intermixed with it; both 
of which would affect the refult in fome degree ;_ but nei- 
ther were of fuch amount as to do fo in any confiderable 
degree. | 
Harpness: fufficient to refift fteel, and {cratch glafs, but 
not quartz. 
Lustre: fhining, approaching to refinous. 
FRACTURE : uneven, verging to flat conchoidal. 
Cotour: pitch black which I confider velvet black with a 
fhade of brown; when pounded, of a greenifh grey co- 
lour. 
Ficure: it occurs cryftallifed. The fimpleft figure, and 
perhaps the primitive form, is a rhomboidal pritm, whofe 
planes meet under angles of 120° and 60°. In fome 
of the fpecimens, the acute angle is replaced by one 
face, in others by two, thereby forming fix and eight 
fided prifms. All the fpecimens I poffels are only frag- 
ments of cryftals, none of which retain any part of a ter- 
mination. They occur imbedded in felfpar, probably gra- 
nite. 
CuemicaL CHaracters: before the blow- pipe froths up, 
and melts but only partially, leaving a brown fcoria ; with 
borax it melts imto a black glafs. When pounded, and 
heated in diluted nitric acid, it tinges the liquid of a ftraw 
colour ; and, fome time after cooling, gélatinates. 
Tue principal diftinguifhing character of the gadolinite, is 
its forming a jelly with acid, a chara&er belonging to few 
other minerals. The Mezotype Lazulite, Apophilite, Adelite, 
and Oxide of Zine, fo far as I know, alone pofleis the fame qua- 
lity ; aud it cannot eafily be miftaken for any of them. 
Bx) 2 Ir 
