MAGNESIA. 
251 
EPSOM SALT. 
[From its having first been found at Epsom, in England.] 
Magnesie Sul-fatee. Haily. — Sulphate of Magnesia. Clcaveland , Phillips and Thomson. — Prismatic Epsom 
Salt. Jameson. — Prismatisches Bitter-Salz. Mohs. — Epsomite. Bcudant. 
Description. Colour white and grey. It occurs regularly crystallized; also in crusts, 
botryoidal and reniform. The primary form 
is a right rhombic prism nearly rectangular. 
Fig. 124. M on M' 90° 30 / . Fig. 125 is one 
of the secondary forms, the pyramidee of 
Haity. M on l 129° 14'; l on l 126° 52'. 
Cleavage perfect parallel to the shorter di¬ 
agonal of the primary. Fracture conchoi- 
dal. Lustre vitreous. Transparent or trans¬ 
lucent. Very brittle. Hardness from 2.0 
to 2.5. Specific gravity from 1.06 to 1.75. 
Before the blowpipe on charcoal, it is con¬ 
verted into sulphuret of magnesium. It dissolves in an equal weight of cold water. Taste 
bitter. The solution gives with potash a white pulverulent precipitate, which becomes lilac 
when it is heated upon charcoal, after the addition of a drop of nitrate of cobalt. 
Composition. Magnesia 10.0, sulphuric acid 32.53, water 51.43. Mg0.S0 3 + 7Aq. 
Geological Situation. It occurs in alum mines, and in several mineral waters. In this 
State, it is almost always found as an efflorescence on limestone rocks. 
LOCALITIES. 
Albany County. Epsom salt, in the form of efflorescences, has been observed in a side- 
hill near Coeymans landing. On the east face of the Helderberg, in the town of Bethlehem, 
near Mr. Fryer’s, it is found in needleform crystals and in crusts on the surface of an impure 
water limestone. It is also found in the town of Guilderland. 
Cayuga County. Epsom salt occurs in the eastern ledge of rocks near the head of Cayuga 
lake, for three or four miles, in connexion with sulphate of iron and thin layers of coal. It is 
also found at the base of a hill on the east bank of 0wasco creek, near Auburn. The same 
mineral occurs on the slate near Ludlowville. Specimens of the latter, received from Mr. 
Vanuxem, were found on analysis to be nearly pure. 
It may be here remarked, that Mr. Vanuxem ascribes the columnar form of some of the 
limestones at the west to the crystallization of the sulphate of magnesia in fibrous crystals at 
the joints of the rock. The carbon which invests the strise was a subsequent action, probably 
a deposition from the same water which dissolved the mineral.* 
Vanuxem. New-York Geological Reports , 1338. 
