PDF BOOK Gems and precious stones : with descriptions of their distinctive properties, the methods for determining them

Gems and precious stones : with descriptions of their distinctive properties, the methods for determining them, &c (1896) To download the book click the link below then click the PDF link on the left hand side of the page. 


BY HENRY G. SMITH, F.C.S.

PREEACE.

IN the preparation of the following notes on " Gems and Precious Stones"
for re-publication, in a form more suited to the requirements of the
general public, it has been recognised that many who feel an interest in
these useful and valuable minerals may have had but little scientific training,
and whose knowledge of gems only extends to those cut and polished
specimens used in articles of adornment. The endeavour has, therefore, been
made to simplify the information, by ignoring scientific expressions and
highly technical terms as much as possible, but where the use of these was
unavoidable, explanatory notes have been added to elucidate their meaning.

It may be well to mention that the natural minerals have but little
resemblance to the finished gems as prepared for sale, and while an attempt
has been made to convey the meaning and appearance of simple crystalline
forms in the four principal systems, it must be understood that it is seldo:
that the natural crystals are perfect in form, or regular in appearance. Thi
might tend to mislead one little acquainted with the laws that govern form
in minerals, although a little consideration would enable one to place a
crystallized specimen in its proper system ; the diamond, the zircon, and the
sapphire for instance, could not be mistaken for each other when found
crystallized, although, perhaps, identical in colour. In water-worn speci-
mens, of course, other tests have to be applied, these are fully described in
the following pages, and the differences pointed out between gems resembling
each other in some respects. The methods adopted in determining the
physical properties of minerals are also fully explained.

It has been attempted, by introducing well authenticated historical facts,
to enliven an otherwise rather dry subject with interesting narrative, much
of which has been obtained from the information collected and published by
Messrs. Streeter, Emanuel, King, Dieulafait, Kunz, Burnham, and others.
To the authors of these works my obligations are due. While endeavouring
to make the information of some educational value, it must be understood
that no attempt has been made to write for those who are already scientifi-
cally acquainted with the subject, as they are well provided for by very
many works of reference.

Technological Museum,

Sydney, New South Wales,

January, 1896.


Link
http://www.archive.org/details/gemspreciousston00smitrich