Properties of Minerals. 91 
VI. HEXAGONAL, or the sia-sided prism (including 
also the rhombrohedral section (R), or the three-sided 
pyramid), in which the vertical axes are at right angles 
to the lateral; the lateral three in number, and inter- 
secting at angles of 60 degrees. (See Dana’s Manual 
of Mineralogy, under System of Crystallization.) 
NINTH PROPERTY. 
. FUSIBILITY. 
The following is the scale of fusibility which has 
been adapted, beginning with the most fusible mineral, 
stibnite, it increases to bronzite, a mineral scarcely fusi- 
ble at all; the scale is, for: 
Stibnite=1.—Fusible in large pieces in the candle 
flame. 
Natrolite=2.—Fusible in small splinters in the 
candle flame. 
Red Garnet=3.—Fusible in large pieces with ease 
in the blowpipe flame. 
Actinolite=4.—Fusible in large pieces with diffi- 
culty in the blowpipe flame. 
Orthoclase=5.—Fusible in small splinters with dif- 
ficulty in the blowpipe flame. 
Bronzite=6.—In the blowpipe flame, scarcely fusi- 
ble at all. 
TENTH PROPERTY. 
SPECIFIC GRAVITY (G). 
The specific gravity of a mineral is its weight com- 
pared with that of distilled water, at 60° F. If a min- 
eral weighs twice as much as a volume of water equal to 
itself, its specific gravity is 2; if three times, it is 3, 
and so on. The most practicable way of determining 
specific gravities is as follows: Take a light glass bot- 
tle (specific gravity bottle) and balance it on the scales 
