1868.] Mineralogy, Mining, and Metallurgy. 103 
opposed by Dr. Wetherill, whose observations show that while the 
micaceous or talcose mineral determines the cleavage of the rock, it 
bears no relation whatever to its flexibility. “This flexibility,” 
says the doctor, “is due to small and innumerable ball-and-socket 
joints.” The grains of silica composing the sandstone, instead of 
cohering into one uniform mass, are arranged in definite groups 
separated from one another by intervening cavities; and when the 
projections of one cluster engage in the corresponding cavities of a 
neighbouring group, there is produced an articulated structure, 
permitting motion within certain limits. By experiment the author 
has found that grains of sand, if saturated with petroleum, will 
cohere into groups separated by such intervening cavities; and 
hence, applying this fact, he conceives that the very gradual re- 
moval of the hydrocarbon might be attended with the separation of 
erystallized carbon in the form of diamond. As the jointed struc- 
ture is quite characteristic of flexible sandstone, the author proposes 
to introduce the term Articulite—apparently a needless multiplica- 
tion of synonymes since the mineral is already well-known as 
Itacolumite.* 
Rarely does the mineralogist meet with a crystal presenting 
that perfect symmetry of form which the laws of crystallography 
demand. As a rule crystals are more or less distorted, the appear- 
ances presented by such irregularities being in many cases extremely 
deceptive. Some curious examples of such monstrosities have lately 
been described by Dr. Scharff, in a paper “On Deformed Crystals 
of Rock Salt.”+ Instead of the six faces of the cube being all 
equally developed, certain faces were drawn out in some crystals 
and depressed in others, thus giving rise on the one hand to pris- 
matic forms and on the other to tabular crystals. Moreover, the 
angles of the cube occasionally deviated from right angles—an 
irregularity giving a rhombohedral aspect to the crystal. In all 
cases, however, the true form was easily discoverable by the cubic 
cleavage. 
In a specimen of Wolfram from Auvergne, Dr. Phipson has 
detected the presence of Columbite. When the mineral is attacked 
by aqua regia the wolfram is dissolved, leaving an insoluble residue, 
which consists of angular fragments of a black non-magnetic sub- 
stance having the composition of Columbite.t 
Some curious numerical relations between the atomic constitution 
of a mineral and the symmetry of its crystalline form have recently 
* “Experiments on Itacolumite (Articulite), with the Explanation of its 
Flexibility and its Relation to the Formation of the Diamond.”—‘Silliman’s 
American Journal,’ xliv., No. 130, p. 61. 
t ‘Ueber missbildete Steinsalz-Krystalle.’ Leonhard und Geinitz’s Jahrbuch. 
1867. Heft vi., p. 670. 
{ “Sur la présence du Columbite dans le Wolfram.”—‘ Comptcs Rendus,’ 1867, 
No. 10, p. 419. 
