Mineralogy of Orange County, N. Y. $29 
ted researches in the soil, until at length a space sixteen feet 
... eight wide and seven deep, has been completely dug over and 
examined. ‘This space was occupied by earth, through which were 
interspersed loose blocks of an aggregate of Limestone Brucite and 
' Serpentine, Spinel in single crystals and in groups, crystals of Brown 
Hornblende and of Specular Iron Ore. These substances appear 
to have constituted, originally, a series of crystalline cavities in the 
Limestone, into which water and soil having freely infiltrated from 
above, they at length became changed to the condition of loose ma- 
terials. ; 
The Spinel is possessed of the following colors: black, greyish 
black, bluish black and reddish brown. ‘The former color has been 
the most abundant: the latter has never been noticed until lately, and 
occurs only in one particular spot in this digging; its gangue is white 
Limestone. The first mentioned colors belong to crystals either 
found loose or associated with the Serpentine and Brucite, and are 
often penetrated by crystals of Specular Iron Ore ; whereas the red- 
ish brown crystals are penetrated by a crystallized mica of the same 
color, the plates of which are disposed parallel with the octahedral 
faces of the Spinel. Nearly all the Spinels of this place are pos- 
sessed of extraordinary dimensions, varying from one to sixteen 
inches round the base. A very common size has been from six to 
eight inches. Nor, as is generally true, is the size at the expense 
of the perfection of the crystal, the largest being equally perfect, as 
respects the smoothness and lustre of the faces, with the smallest. 
We frequently observe a tendency of smaller crystals to unite to 
ma large one, or of a great number of crystals conneeted in such 
amanner that their similar faces are parallel. The only form be- 
side the primitive, in this mineral, is the ordinary hemitrope ; of which 
several of enormous size are said to have been found. But they 
have not often been met with of late at this locality. 
The crystals of Specular Iron, above allu- 
‘to, and which are almost invariably found 
Penetrating the Spinel, are extremely inter- 
‘sting on account of their size and form. 
Por a long time their true character appears 
10 have been misunderstood; and they are 
stil often found in cabinets under the name of 
laniferous Iron, or believed to be some undescribed ore of Co- 
Vou. XXI.—No. 2 42 
