New Locality of Amethyst. 199 
New Bey of Amethyst.—Communicated by Pro- 
fessor J. Apams. 
Amethysts have lately been found at Bristol, Rhode Isl- 
and. ‘The locality is on the shore of Mount Hope Bay, 
a branch of Narragansett Bay. A large number of speci- 
mens has been found, some of which are regularly crystalli- 
zed. A few are large and beautiful. ‘Two or three have 
been wrought into elegant personal ornaments. Many of 
the specitnens have been procured from among the sand 
and gravel, at and near low water mark. This sand is 
formed by the constant decomposition of an immense 
mass of rock, which rises in a precipice of considerable 
height, close upon the shore. Some specimens have been 
discovered by digging into the rock, especially that part of 
it which contains quartz. Most of the mass of rock in 
question, is feldspar nearly pure. Very minute specks of 
mica are scattered through it, but they are extremely rare. 
The mass is occasionally traversed by thin strata of quartz, 
nearly in a vertical situation. 
At this locality of amethysts 1 found also, two specimens 
of micaceous iron, and upon the shore near the same 
place, a great number of crystals of iron. (Sulphuret of 
iron.) Many of them are very large, crystallized in cubes, 
whose sides are from a half to three quarters of an inch 
square in their dimensions. They are imbedded in a 
hard, light coloured clay slate. This locality of amethysts 
is about two miles from Bristol village, and near the ferry 
which leads from Bristol to Rhode Island. 
The region in which these minerals are found, is a part 
of the transition formation which extends from Narragan- 
sett to Massachusetts Bay. This traasition formation rests 
upon a primitive foundation, and does not appear to be 
very thick; since in sinking walls, we sometimes penetrate 
into the primitive rocks, and in some places, the primitive 
rises upwards through the incumbent transition formation. 
This is the case with the summit of Mount Hope, which is 
granite, and with the mass of rocks which form the locality 
of amethysts above mentioned. 
