228 W. P. Blake on Crystallized Carbonate of Lanthanum. 
Arr. XXIV.—On the occurrence of Crystallized Carbonate of 
Lanthanum ; by W. P. Brake. 
~ Tue mineral I am about to describe was found near Bethlehem, 
in Lehigh Co., Pa., associated with the zinc ores of the Saucon 
Valley. It was thrown out from a few feet below the surface, 
by the miners when sinking an exploring shaft near one of the 
veins of calamine in limestone. A single specimen of the mineral 
was preserved by Dr. W. W. Dickenson the superintendent, who 
at my request furnished me with a part of it for examination. 
The specimen was about three inches in diameter and attracted 
my attention by its delicate pink color and peculiar structure, be- 
ing an aggregation of thin plates and scales of a pearly luster, 
forming a light reticulated mass which was found to be highly 
crystalline on examination by a glass, and the crystals were 
apparently rectangular in form. A more satisfactory examina- 
tion of them was made by placing some loose fragments upon 
the stage of a microscope, and viewing them with a glass of 
moderate magnifying power. The appearance in the field of the 
instrument was beautiful and exceedingly interesting, each minute 
fragment being a part of a well formed tabular crystal, and retain- 
ing many of its edges and angles. It became evident that the 
angles formed by the meeting of the principal edges were oblique. 
ach large crystalline plate had upon its broad surface one oF 
more smaller crystals. 
Two of the forms observed are here represented. 
r: 9. 
The edges of all the crystals appeared to be beveled, and one 
or two were seen on which there was a double bevelment as re- 
presented in the second figure. 
The crystals were so very thin that it was not possible to meas- 
ure the inclinations of these planes. 
I however obtained the angles of the tables by the aid of the 
rotating eye-piece micrometer attached to Nachet’s large muicro- 
scope. ‘I'he crystal gave the angles 94° and 86°. 
