’ 
250 DESCRIPTIONS OF MINERALS. 
calcium-iron amphibole. Glassy actinolite includes the bright 
glassy crystals,.of a rich green color, usually long and slen- 
der, and penetrating the gangue like tremolite. Radiated 
actinolite includes olive-green masses, consisting of agere- 
gations of coarse acicular fibres, radiating or divergent. 
Asbestiform actinolite resembles the radiated, but the fibres 
are more delicate. Afassive actinolite consists of angular 
grains instead of fibres. G.=3°0-3'1. The name actino- 
lite alludes to the radiated structure of some varieties, and 
is derived from the Greek, aktin, a ray of the sun. 
Asbestus. In slender fibres easily separable, and some- 
times like flax. Hither green or white. Amianthus, in- 
cludes fine silky varieties. (Much so called is serpentine ; 
serpentine is hydrous, and is thereby easily distinguished.) 
Ligniform asbestus is compact and hard ; it occurs of brown- 
ish and yellowish colors, and looks somewhat like petrified 
wood. Mountain leather occurs in thin, tough sheets, look- 
ing and feeling a little like kid leather ; it consists of inter- 
Jaced fibres of “abestus, and forms thin seams between layers 
or in fissures of rocks. Mountain cork is similar, but is in 
thicker masses ; it has the elasticity of cork, and is usually 
white or orayish white. 
The preceding light-colored varieties contain little or no 
alumina or iron. 
Composition of glassy actinolite: Silica 59°75, magnesia 
21:1, ime 14°25, protoxide of iron 3:9, protoxide of man- 
ganese 0°3, hydrofluoric acid 0:8 (Bonsdorf). : 
Nephrite is a very tough compact variety, related to tre- 
molite. Color light-green or blue. It breaks with a splin- 
tery fracture and glistening lustre. H.= Gls) aca 
a magnesium-calcium amphibole. Nephrite is made into im- 
ages, and was formerly worn as a charm. It was supposed to 
be a cure for diseases of the kidney, whence the name, from 
the Greek, nephros, kidney. In New Zealand, China and 
Western America, it is carved by the inhabitants, or pol- 
lished down into various fanciful shapes. It is called jade; 
but the alurainum-sodium silicate, called jadeite, is the stone 
most highly prized of all those that are called jade. Much 
of the mineral from China called jade is prehnite. 

II. DARK-COLORED VARIETIES. 
Cummingtonite is a» magnesium-iron amphibole. Color 
gray or brown ; usually fibrous. Named from the locality 
where found, Cummington, Mass. 
P= Pe fe 

