SILICA. 
283 
St. Lawrence County. Chondrodite is found in white limestone on the bank of Laidlaw 
lake, in the town of Ilossie, about two miles north of the village of Oxbow. It is in the form 
of small yellow grains, but it is not abundant. 
Again, two miles from Somerville, in the same town, it occurs nearly of the same colour, 
associated with light blue spinelle. It is near the locality of buff serpentine and mica. 
With the above exceptions, I know of no localities of this mineral in Northern New-York. 
It has, however, long been placed among the minerals of Rogers’ rock, but I have never met 
with it at that locality. 
In New-Jersey, chondrodite has been found abundantly in the county of Sussex, which 
adjoins that of Orange, N. Y. 
BOLTONITE. 
[From Bolton in Massachusetts, where it was first found.] 
Boltonite. Shepard and Dana. 
Description. This mineral, which, however, is still a doubtful one, has heretofore been 
found only massive. Its fracture is coarsely granular. Colour bluish grey, yellowish grey, 
wax-yellow to yellowish white. Streak white. Cleavage pretty distinct in one direction ; in 
two others oblique to the first, indistinct, but affording indications of a doubly oblique prism 
for the primary form. Fracture uneven. Lustre vitreous. Transparent to translucent. Hard¬ 
ness from 5.0 to 6.0. Specific gravity from 2.80 to 2.90. Before the blowpipe, it becomes 
white and transparent, but is infusible ; with borax, it yields a transparent glass. 
This mineral was first found at Bolton, Mass., whence the above name was given to it by 
Mr. Nuttall. Dr. Thomson, several years since, described it under the name of Silicate of 
magnesia ;* but in his Outlines of Mineralogy, he remarks that it is intimately connected 
with picrosmine, with which it also sufficiently agrees in chemical composition. Many of 
the specimens so closely resemble chondrodite, that it is almost impossible to distinguish them 
by their external characters. They differ, however, in the proportions of silica and magnesia 
which they contain. 
Composition. Silica 56.64, magnesia 36.52, alumina 6.07, protoxide of iron 2.46 
( Thomson ). 
Geological Situation. Boltonite has heretofore been found only in white limestone. 
localities. 1 
Orange County. Dr. Horton has introduced into his catalogue, three or four localities of 
boltonite; and the specimens from some of these have been recognized as identical with 
* Annals of the Lyceum of Natural History of New-York. III. 50. 
