ON THE KLAPROTHINE OR LAZULITE OF NORTH CAROLINA. 367 
a tetartohedral modification. It is a mere line, dull like the other 
planes, and too narrow to admit of satisfactory measurement. The 
crystals are sometimes implanted in one another, but I have not 
detected any definite twin-combinations. The crystals extracted from 
my specimen, together with those exposed on the surface of this, do 
not amount however to more than ten or twelve in number. The 
hardness of these crystals is equal to 5.75, or very nearly to 6:0. 
The sp. gr. (one determination only) [ found to equal 3108, a value 
corresponding sufficiently with that obtained by Smith and Brush 
(3°122). The cleavage I have not been able to determine in a satis- 
factory manner. The blow-pipe reactions are as follows : 
In the closed tube, the assay gives off water and loses its colour, 
becoming yellowish or greyish-white. 
Per se, it exfoliates and expands greatly in bulk, changes colour, 
tinges the flame green, and crumbles away without fusing. 
Tn borax, it dissolves very easily, imparting to the glass a pale 
ferruginous tinge. 
In salt-of-phosphorus, it dissolves also very readily, and with slight 
effervescence. 
In carbonate of soda it dissolves partially, but the dissolved portion 
is in great part precipitated as the glass cools, forming a white 
enamel. If the bead be dissolved in a little boiling water, a drop of 
nitric acid added to decompose the excess of carbonate of soda, and 
the clear supernatant liquid be then poured upon a small crystal of 
nitrate of silver, a yellow precipitate of phosphate is at once obtained. 
In employing this test for phosphates, the beginner should be caution- 
ed, however, that silicates (if decomposable by carb. soda,) will 
produce the same reaction, but the silica may be eliminated by adding 
several drops of acid, and evaporating to dryness. By treatment 
with salt-of-phosphorus, moreover, silicates are at once recognized. If 
the solution of our mineral, as obtained above, be treated with acetate 
of lead, the precipitate presents the well-known blowpipe reaction of 
phosphate of lead, ¢.e., the formation of a faceted globule without 
reduction. 
Two analyses of the North Carolina lazulite are given by Professors 
Smith and Brush in the American Journal of Science and Arts for 
September, 1853. These exhibit the following results : 
