Reéramination of American Minerals. 373 
3:008 as its specific gravity, with a hardness of from 5 to 6: his 
analysis gave for its constituents :* 
Silica, . 46062 
lumina, 5667 
Magnesia, : 38149 
Protoxyd of iron, 8632 
ime, . : 1516 
the gangue, made it very evident that the mineral was more or 
less mixed with other substances which had escaped observation, 
for no two analyses agreed; and it was soon discovered that it 
was impossible (from the specimens in my possession at least) to 
separate Boltonite in a state of purity without the aid of other 
means than had been adopted. 
Boltonite, as is well known, occurs at Bolton, Mass., er: 
_ted in irregular masses and grains in a white limestone. 
piece of the mineral in its gangue be placed in cold dilute hydro- 
chloric acid, the limestone is readily dissolved, and a mass left, 
which is seen to consist of asbestus, dolomite, a little mica, small 
crystals of magnetic iron, and a greenish or yellowish green min- 
eral; if the acid be now heated, the dolomite will be entirely 
dissolved with a little of the last mentioned mineral. 
In order to obtain the Boltonite as pure as possible for analysis, 
the following method was adopted. Pieces were separated by 
the hammer as thoroughly as possible from all other substances ; 
these were subsequently placed in dilute hydrochloric acid, and 
boiled for some time; the acid being washed away and the sub- 
stance dried, it was crushed in a mortar to fragments from the 
twentieth to the tenth of an inch in diameter; these were again 
introduced into dilute acid and heated fora short while; the acid 
was thoroughly washed away, and the mineral dried. The small 
fragments (now like coarse gravel) were placed on a piece of 
glazed paper, the hand laid flat upon it and the mineral rubbed 
80 as to grind the particles against each other for the purpose of 
ridding their surfaces of a little cohering silica arising from its 
partial decomposition ; with a small gauze sieve the finer particles 
are separated, and from that remaining in the sieve we are enable 
With the aid of a glass without any difficulty to pick out the pure 
Boltonite. This method requires a little patience, but no extra- 
ordinary care, and however unpromising the original specimens 
may have been, there is no difficulty in obtaining a material, the 
results of whose analysis is constant. From a larger selection of 
Specimens than that used, there doubtless could be obtained pieces 
Perfectly pure of some size. After being satisfied with this method 
of obtaining the pure mineral, three different portions were pre- 
* This Journal, vol. viii, 2d ser., p. 391. 
