44 COMMON QUARTZ. 
is cut into stones for rings and other ornaments. Ve- 
suvian has of late years been found in other parts of 
Europe ; and even at Kilranelagh, and Donegal, in 
Ireland. 
75. CINNAMON STONE is a Jdndof garnet of kyacinth- 
red colour, which is found in angular and roundish 
pieces among the sand of rivers in the island of Ceylon. 
It is cut as a precious stone ; and, when of good colour, 
and free from flaws, is of considerable value. 
QUARTZ FAMILY. 
76. COMMON QUARTZ is a hard and foliated sub- 
stance, usually of white or grey colour, and more or less trans- 
parent. 
It is generally found in shapeless masses, which are nearly 
thrice as heavy as water, and the fracture of which is glassy. 
When crystallized, it most commonly has the form of a six-sided 
prism, terminated by a pyramid of six sides. 
This kind of stone forms a constituent part of many 
mountains, and is very common in our own, as well as 
in most other countries. It is sufficiently hard to scratch 
iron and steel; and it has the property, after having 
been several times successively made red-hot, and dip- 
ped into water, of communicating to that fluid a certain 
degree of acidity. 
Quartz is employed, in place of sand, for making the 
finer kinds of glass ; and also in the manufacture of 
porcelain. For the latter purpose great quantities are 
collected from the mountains of Wales, ground into 
powder, and in that state shipped to Liverpool, and 
other parts. After having been burnt and reduced to 
powder, it is sometimes mixed with clay, and formed 
into bricks for the construction of glass furnaces : these 
are capable of resisting the intense heat which is requi- 
site in the fusion of glass. 
77. BURRSTONE is a vesicular and corroded variety 
of quartz, which forms a most excellent and valuable 
