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10 THE PACIFIC MINERALOGIST

Digressing from the subject for a
moment I might say that there is a
very fertile field for experiment and
pleasure for those who have a micro-
scope. Equip it with a set of polar-
izers and see what luck you have
in identifying the minerals. I have
had pretty good luck cutting and
polishing this material, and for those
tion to one another. Chert Nodules who cut and polish their own speci-
are often formed and found in bed- mens, I will say that you will find
ding of this sort. In other words, it easy to cut and easy to polish, as
the first piece of material I picked it is not too hard and it is not sensi-
up looked exactly like bone, and tive to burning on the sander. I
some of the others do too, but not all should judge that it has a hardness
of it. Attention is drawn to the color of five or five and a half on the aver-
of one, which is distinctly black, or at age and there are no tricks which I
least very dark brown on the inside, can teach any of you as I have only
while the outer layers are greyish been grinding for three years. I mount
to white. When polishing it there is ed these
a very noticable odor of fish. specimens on
~ - ___,e;'!==:;;~;.Jjll:IIIIS(>'Lj~ bases o f
I have done some work on the bakelite and
identification of these materials by an attempt
making some thin pieces of the vari- has been
ous kinds. These were not the ultra made to decrease the brilliance of
thin kind of only a fraction of a thous- them so that the bone looks better.
andth of an inch thick such as are These pieces were cut on an eight
made and examined by Mr, Roy inch diamond saw and lapped on a
Martindale, (I am not that smart yet) horizontal lap twelve inches in diam-
they were just some very thin speci- eter. The sanding which followed
mens which I ground on a plate of
glass with some No. 600 fine carbor- was done with number 220, then
number 400, then on the leather
undum powder and mounted on mi- wheel with tin oxide.
croscope slides. These were illumin-
ated by transmitted light and ex- I do not claim that these speci-
amined through a Wratten filter and mens are beautiful, but I do know
through a system of polarizers which I had fun and added to my store of
-I have in my microscope. With this mineral know ldege with them. I think
setup it is possible to identify the the element of great age and the
tiny, oval, wheatseed looking osteo- fact that here at last is something
blasts in the structure which 'f know that was once alive makes for more
for bone and which I know could not interest in these old timers.
have been formed by the solidifi- If there is any doubt about the
cation of silica gel. I do not know the
magnification which I used in these authenticity of this find or this classi-
experiments but it was probably fication, let me say that it makes a
more than 200X. good story anyway.