220 DESCRIPTIONS OF MINERALS. 
extensively as marble. The magnesian lime has been sup- 
posed to injure soils; but this is believed not to be the case 
if it is air-slaked before being used. It is also employed in 
the manufacture of Epsom salts or magnesium sulphate. 
Ankerite. Resembles brown spar, and, like that, becomes brown on 
exposure. Fundamental from a rhombohedron of 106° 12. Itis a 
calcium-magnesium-iron-and-manganese carbonate. The Styrian iron 
ore beds of Saltzburg are some of its foreign localities. It occurs in 
Nova Scotia, and in quartz veins in Western New Hampshire ; Quebec, 
Canada, etc. 
Hydrodolomite. A calcium-magnesium carbonate containing water. 
Pennite from Texas, Pa., is similar. 
BARIUM anp STRONTIUM. 
Barium and strontium occur in nature only in anhydrous 
ternary compounds of the following kinds: sulphate, car- 
bonate, silicate ; and in silicates only in combination with 
other basic elements. The species are characterized by high 
specific gravity, ranging from 3°5 to 4:5. Strontium gives 
a red color to the blowpipe flame ; and barium, if strontinm 
and other basic’elements are absent, a characteristic green 
color. 
Barite.—Heavy Spar. Barium Sulphate. 
Trimetric. In modified rhombic and rectangular prisms, 
PAL=101° 40';, OAPI=141° 08» OAS 127 
tals usually tabular. Massive 
varieties often coarse lamellar ; 
also columnar, fibrous, granu- 
lar and compact. Lustre vitre- 
ous; sometimes pearly. Color 
white and sometimes tinged 
yellow, red, brown,- blue, or 
dark brown. Transparent or 
translucent. .H.=235-—3'5. “Ge 
Composition. Ba 0, Sy 
Sulphur trioxide 54:3, baryta 
65°7=100. Strontium and cal- 
cium are sometimes present re- 
placing a little barium. B.B. 
fuses to a bead which reacts 
alkaline. Imparts a green color to the flame. After fusion 

