298 
DESCRIPTIVE MINERALOGY. 
HORNBLENDE. 
Amphibole. Hauj and Thomson. — Hornblende. Phillips, Shepard and Dana. Hemiprismatic Augite. Jameson. — 
Hemiprismatischer Augit-Spath. Mohs. 
Cleaveland includes under Hornblende only the dark-coloured varieties. He has Tremolite as a distinct species, and 
Actynolite as a subspecies under Hornblende. Beudant has a subgenus Amphibole, and under it he places Tremolite 
and Actinote as species. Phillips includes under the general name Hornblende, Common Hornblende, Pargasite, Tre¬ 
molite, Pyrallolite, Actynolite, and Asbcstus. As it is exceedingly difficult to draw the line between these varieties, I 
shall follow this author. 
Colour green, white, black, grey, blue and brown. It occurs regularly crys¬ 
tallized ; also in lamellar and fibrous masses. Primary form an oblique 
rhombic prism. Fig. 223 (bis). M on M / 124° 30 / ; M or M' on P 103° 
lfi Cleavage parallel with M highly perfect; less distinct parallel with 
P, and with the diagonals of the prism. Fracture conchoidal, uneven 
and slaty. Lustre vitreous, vitreo-pearly, pearly and vitreo-resinous. 
Ranges from transparent to opaque. Hardness from 5 to 6. Specific 
gravity from 2.90 to 3.35. Fusible before the blowpipe, with more 
or less ease, into a white translucent or opaque glass, or into one that 
is green or black, depending upon the variety. It is not easily attacked 
by acids. 
Hornblende is distinguished from diallage and hypersthene chiefly by its cleavage. Diallage 
has only one distinct cleavage; hypersthene three, of which two are silvery, and one copper¬ 
like ; while hornblende has only two, and moreover by transmitted light displays a deep red 
colour. It is more difficult to distinguish hornblende from pyroxene. Prof. G. Rose has in¬ 
deed proposed to unite them, and he has presented a great number of facts in favour of their 
identity.* 
Varieties. Hornblende — Carinthin. This includes all those varieties with dark green 
and black colours, whether crystallized or massive. The lustre varies from pearly to pearly- 
vitreous. It is usually opaque, and before the blowpipe, fuses into a black brilliant glass. 
The term basaltic has been particularly applied to those cleavable and highly crystalline black 
hornblendes which occur in basaltic and amygdaloidal rocks. 
Pargasite. A name originally given to a hornblende from Pargas in Finland. It is somewhat 
translucent, and is usually of a bottle-green colour. In other respects, it agrees with the 
preceding variety. 
Actynolite and Calamite. These are light green, greenish grey, and sometimes brown and 
yellow. They are seldom crystallized, (and then generally in reed-like crystals ;) more fre- 
Description. 
Fig. 223 (bis). 
Allan’s Manual of Mineralogy , 149. 
