SILICA. 
279 
here be obtained, but in some cases they will be found so closely associated with each other, 
that a specimen of ordinary size will frequently exhibit the gradual passage between the most 
widely different varieties. 
MAGNESITE. 
Magnesite. Cleaveland, Beudant. — Meerschaum. Werner. — Bihydrous Tersilicate of Magnesia. Thomson. — 
A variety of the Prismatic Talc Mica of Jameson , and of the Prismatischer Talc-Glimmer of Mohs. — Kero- 
lite. Shepard. — Kerolite, and Hydrous Silicate of Magnesia. Dana. — Marmolite. NuttaU and Beudant. 
Under the general name of Magnesite, I include several minerals which are essentially 
composed of silica and magnesia, and none of them containing any notable proportion of the 
carbonate of magnesia. 
Description. Colour white, greyish, bluish, yellowish or reddish white. It always 
occurs massive, often tuberous and reniform. More or less earthy, always very tender. The 
powder is tolerably hard, and it has usually a smooth and unctuous feel. Fracture earthy and 
conchoidal. Hardness from 2.0 to 3.0. Specific gravity of magnesite from 2.60 to 3.40 
{Beudant)-, of meerschaum, from 0.98 to 2.12. By calcination, it gives out water. It is 
with great difficulty fused by the blowpipe into a white enamel. It is partially acted on by 
acids. 
Varieties. Magnesite. Greyish white, with a tint of red. It is soft, has a smooth and 
unctuous feel, but its powder is pretty hard. 
Meerschaum. Colour snow-white. Fracture passing into flat, conchoidal. Surface smooth ; 
fine grained. Sometimes it is very soft, and has the appearance of being a deposit from 
water. 
Composition. Magnesite —Silica 54.00, magnesia 24.00, water 20.00, alumina 1.40 
( Berthier). 
Meerschaum —Silica 42.00, magnesia 30.50, water 23.00, lime 2.30, alumina with a 
trace of manganese 2.00 {Thomson). 
Marmolite, from Hoboken, N. J .—Silica 40.00, magnesia 42.00, water 16.45, deutoxide 
of iron 0.90 {Vanuxem). 
Kerolite —Silica 37.95, magnesia 18.01, water 31.00, alumina 12.18 {Pfaff). 
Deweylite —Silica 40.00, magnesia 40.00, water 20.00 {Shepard). 
Geological Situation. All the different varieties of this mineral are found in veins in 
serpentine, and sometimes in veins of trap. They are very closely allied to serpentine, with 
which this species ought perhaps to be united. 
localities. 
Orange County. Near Greenwood furnace, magnesite of a greyish and yellowish white 
colour, occurs in veins of from a quarter to half an inch, in serpentine. It is associated with 
asbestus, but it is not abundant. 
