202 Notes on “ Inclusions” in Gems, &c. By Isaae Lea. 
detected them only in a specimen from Unionville, Penn. In 
this there is a biangular cavity with a small cubic crystal at 
an inner angle. Throughout the mass there are small suboval 
cavities. 
Garnet.—As a precious stone this is by no means rare, but it 
is lustrous, and of a fine colour. Cavities and microscopic crystals 
are very common in this gem.* The cavities are usually irregular 
and rough, and never to my knowledge have fiuid. On a polished 
surface of a piece of garnet from North Carolina, nearly an inch 
long, the reflexion of these crystals covered the whole surface with 
prismatic colours. 
Cinnamon Stone.—This beautiful variety of garnet, from 
Ceylon, as far as I have been able to observe it, and I have some 
twenty cut specimens, and numerous rolled pieces, has irregular 
cavities and some crystals, as I have stated in a former paper. 
Zircon.— With its high refractory power, this is used frequently 
as a gem, and sometimes sold as a diamond when white and per- 
fectly transparent. One of the numerous specimens which I have 
examined has cavities t and microscopic crystals, and a specimen 
from Ceylon has remarkable dark brown, elongate, fusiform spots, 
with numerous dotted ones intervening. 
Chrysoberyl.—The few specimens I have of this beautiful gem 
have neither cavities nor microscopic crystals, but Brewster ob- 
served “strata of cavities and both the fluids.” 
Chrysolite = Olivine.—In some of my specimens I have 
observed small cavities with fluid. Brewster met with them con- 
taining “ fluid and bubbles of air.” 
Spinel.—This gem occurs of several colours. The Spinel ruby, 
so called, sometimes is very close in colour to the true ruby, but it 
has not by any means the depth nor brilliancy of the true ruby. 
In a pale-green specimen of great beauty which I have received 
recently from Ceylon, I have not been able to detect cavities or 
crystals. In my former papers I have expressed uncertainty in 
this matter.f 
Jolite—This gem is inferior in hardness, colour, and specific 
gravity to sapphire, but is valued for its peculiar change of colour, 
being dichroic. One of my specimens is without any inclusions. 
The other is filled with blue four-sided prismatic crystals, which are 
long, and enclosed in a nearly white subtransparent mass, These 
erystals are sometimes broken and their parts prolonged in the 
mass, and they are all lying in nearly the same direction. 
Turquoise, with its peculiar and agreeable blue, is never trans- 
parent, and neither cavities nor microscopic crystals are found in it, 
* ¢Proc. Acad. Nat. Sci.” February and May 1869. 
+ In a specimen in Dr. Leidy’s fine cabinet there are anastomosing cavities. 
+ ‘Proc. Acad. Nat. Sci.’ February and May 1869, 
