368 A. A. Julien on Minerals of the Key of Sombrero. 
(2.) Hollow crusts, formed by the removal from the former of 
their cores of carbonate of lime. 
(3.) Solid crystals, wholly consisting of the phosphatic material. 
2. Common Sult.—The numerous pools of sea-water alon 
were saturated with sea-water. The waters soon subsided 
through the bottom of the quarry and a peculiar efflorescence of 
sed to the atmosphere. This crust consisted of slender crystals, 
usually one-eighth of an inch in length, white, translucent, and so 
uch curved as to take, in some cases, one and a half turns, or to 
Teturn to and become re-embedded in the matrix. In this last 
characteristic and in their fibrous structure they strongly resem- 
ble, especially under the microscope, the similar forms of gyp- 
sum, etc. fracture uneven. A tendency is shown, (by the 
ge, marked by the numerous lines of 
cross-fracture. In the thicker crystals the breadth is, in most 
ases, nearly uniform throughout their length; but in others it 
often d creases from one end to the other. The outer termina- 
a sphere of greater diameter. The tran 
crystal is apparently almost circular, though irregular. 
ng t. iS: 
es L IL. 
Moisture (expelled at 100°C), - - - 34 — 
Loss by ignition, — - ee ae 
see cia 2 cose 
ge cle 
