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66 Practical Remarks on Gems. 
emery paper ; it is also used extensively for the polishing of eut- 
lery, and even of some of the gems. It occurs in long six-sided 
crystals, and in other forms in which the original crystals are so 
abraded that their form cannot be distinguished; in color it is 
very dull, sometimes of an indefinable brown, green, red and 
ray. 
10. Hypersthene, is the very opposite of corundum in consis- 
tency, being as soft as the other is hard ; neither is it so useful, 
though it is said sometimes to have figured in jewelry. It must” 
have made a very uninteresting appearance, as it bears but an in- 
different polish. Its color is greenish black or brown; it is very 
abundant on the banks of the Brandywine, althongh of a very poor 
kind ; but I have just seen some beautiful specimens from Massa- 
. sieoenta: Although it appears | to be in some repute with the + 
French, for jewelry, it is plone unknown to North American 
jewellers. 
ll. Red Oride of nkian, is used by the dentists to impart 
a tinge of color to their porcelain or incorruptible teeth which ren- 
ders them more natural in their appearance. The color of this 
is a copper red, approaching to brown, of metallic lustre, and when 
found together with quartz, its appearance is very beautiful, 
sometimes passing through the erystals in minute hair-like fibres.* 
12. Sphene, (Calcareous Oxide of Titanium.) Is but a vati- 
ety of the preceding, and embraces such a range of form and color 
as to render it difficult of recognition, except to those well versed 
in the study. It is of a lustre Jess metallic than the above ; it is 
opake and much harder; it may easily be mistaken for the brown, 
* 
garnet, which however is of greater tenacity and different struc- 
ture. - 
13. Spinelle. In color it is either red, brown or black with all 
their intermediate shades and modifications; it is found in granu- 
lar and angular fragments, and octahedral crystals; those of @ 
crimson color are much xeed 3 in fine jewelry under the name of 
spinelle ruby, as also the rose-red or pink, which is styled the Ba- 
las ruby; that of a violet color, closely resembles the Almandine 
garnet, and is known as the Almandine ruby. ‘There are othel 
ial 
_ Varieties, such as the orangine or rubicelle. 
* The rulite of Middletown, in Connecticut, forms a most beautiful gem. It 
has recently been gee out by Prof. C. U. Shepard, from London, polished 4” wf 
Eps, : 
set, and almost rivals the fib 
ia 
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tame seat 
