|
UNITED STATES, CANADA AND MEXICO
|
181
|
||
|
|
|||
|
its
name from its green color and banded appearance, from zona, a band,
chloros, green, and lithos, stone. It takes a high polish, but it has
been used only to a limited extent as a mineralogical gem.
Chlorastrolite is found only on the Isle Royale, Lake Superior. This
island, which belongs to the State of Michigan, is forty miles long
and five miles broad, and is about twenty miles from the mainland. The
only inhabitant of the island is the lighthouse keeper, who, from time
to time, entertains parties who come to fish or mineralogists who come
for chlorastrolites. The underlying rock is an amygdaloid trap, in
which the gem is found, but it is now collected in the form of rolled
pebbles on the beach, having fallen or weathered out of the trap rock.
It is entirely opaque, of green color, mottled and stellated, and
admits of a high polish. Sometimes the stellations radiate from the
centre,
|
|||
|
|
|||
|
CHLORASTROLITE
|
|||
|
|
|||
|
|
|||
|
|
|||
|
and
show a beautiful chatoyancy, similar to the cat's-eye, crocido-lite,
and other fibrous minerals. Prof. A. E. Foote and a party camped for
some months on this island in 1868, and chlorastrolite was first found
by them in a -vein-stone associated with native copper and epidote.
Rounded pebbles of the rock containing the chlorastrolite are
plentiful on the beach. One of the largest known perfect
chlorastrolites is in the cabinet of M. T. Lynde, of Brooklyn, N. Y.,
and measures 1-1/2 by 1-1/8 inches (see Colored Plate No. 3) ; next in
size is one belonging to Alfred Morrison, of London; and the third
largest is owned by an American lady, now residing in London. A fine
pair of oval chlorastrolites, over half an inch in length, are in the
possession of Frederick A. Canfield, of Dover, N. J. About $1,000 worth
are annually sold to tourists.
Thomsonite and lintonite, the latter first described by Peckham1
'Am. J. Sci. III., Vol. 19, p. 123, Feb., 1880.
|
|||
|
|
|||