THE N^ATURAL SCIENCE JOUENAL. 
15 
to be valuable as a cure for diseases of 
the kidneys, hence its name. It is often 
cut into images and charms. 
Of the dark-colored varieties, horne- 
blende is the most important, but does 
not differ essentially from the rock of the 
same name. Hornebleude Schist is strati¬ 
fied quartz and horneblende. The quartz 
is usually granular, while the horneblende 
takes the form of bladed crystals, both 
finely and coarsely crystalline. Garnet 
is a common accessory mineral. 
Another variety is Cummingtonite, 
named for Cummington, Mass., where 
it is found. It is fibrous and of a dark- 
grayish color. 
OALOITE. 
ALCITE is next to quartz, the most 
interesting of all minerals, and 
though its inferior hardness prevents its 
use for lapidary work, it is in some re¬ 
spects even more useful and more inter¬ 
esting than quartz. 
It crystalizes in the same system, the 
hexagonal, but is more diversified in 
form. As many as seven hundred forms 
are claimed by some writers, yet these 
are all reducible to the Primitive Type — 
the Rhombohedron; a wonderful illus¬ 
tration of the simplicity of Nature in the 
midst of diversity. 
It agrees also with quartz in lustre and 
specific gravity. In fact, the more we 
compare the two minerals, we are sur¬ 
prised at the remarkable similarity be¬ 
tween them, both in regard to properties 
and uses. In color, every imaginable 
shade is represented. 
If the classification be extended to in¬ 
clude all the calcium-bearing minerals, 
they will be found to present a bewilder¬ 
ing variety. 
Of the six systems of crystalization? 
no less than four are represented, and 
probably a variety of forms that will 
extend into the thousands. They will be 
found to vary in hardness from one to 
four, with a corresponding variation in 
specific gravity, In composition, lustre, 
and color, there is an equal variation, as 
also in regard to use. 
Surely here is a wide field for investi¬ 
gation. While the mineral world has 
gone mad over quartz, let someone come 
forward as the apostle of calcite. 
QUESTIONS. 
[We give our readers a few questions to 
answer this month. This department can be 
made one of the most interesting and instruc¬ 
tive features of tlie journal. Let us make it 
so. Send in your questions and answers. 
Anything of general interest will be welcome. 
If it provokes discussion or criticism, so much 
the better, provided it be not of a personal 
nature.] 
What is an :s^ld specimen? 
— J. C. H. 
Will someone please give a simple, but 
scientific method for labelling and arrang¬ 
ing specimens on the shelves? — R. H. 
Not long since, I was examining a 
group of quartz crystals, when, to my 
surprise, I found that the long facets of 
the pyramids all faced the same way. 
I turned to other groups to see if the 
law was universal. I found no excep¬ 
tion to rule, and further, I found that, 
where the crystals were horizontal or 
oblique, the long facets were usually on 
the upper side of the crystal. This may 
not be anything new but it was so to me, 
and I would be very glad if some of the 
readers of the journal will kindly explain 
the cause of it.—M. T. C. 
