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“beds is between the gypsum and the limestone proper. These 
“beds are generally in proximity to the sea.” * 
We now adduce observations upon examples of Celestite 
from the rich mines of Lercara Friddi, lying to the N. West 
of the Girgenti Valley, with shafts of about 300 or 400 feet 
in depth driven through strata of Hocene age, and into light 
erey marls. The Professor of Geology at the Royal University 
of Palermo, Signor Gemmellaro, kindly assisted the writer, not 
only in his examination of the valuable collections of fossils and 
minerals of that institution, but directed him to visit the works 
at Lercara, which he found valuable in respect of gaining in- 
sight into the exploration of the formation. From specimens 
thus procured, the first example will be from the Calcedone (a 
miner’s name), which forms the spoil banks of the workings. 
In one mine here about 800 men and boys are at work. 
1.—Calcedone: very pale grey, in colour verging on white, 
lamellated ; the layers are of gypsum and pale sulphur alter- 
nately, in contact. The marl about from 6 millimétres in 
thickness to double that. thickness, or more, the light sulphur 
not more than from 1 to 2 millimétres in thickness, deposited 
regularly in films. The Celestite forms a capping of a dull 
white, and semi-crystallization, exactly like our ordinary loaf 
sugar. This specimen is exceedingly instructive, showing 
plainly the bubbling of the hydrogen sulphide gas depositing 
the sulphur in films, and leaving the incipient crystals of 
Celestite as the top layer, separating out from the sulphur, 
which forms amorphous blebs or clots, and has not begun to 
crystallize. The whole piece is traversed by vertical fissures, 
ending in holes, through which the gas issued, and has traces 
as of bubbles of sulphur bursting and leaving concave films of 
that substance. It is clear that this marl was mud. 
2.—Calcedone. This specimen discloses an action of a 
slower character. It may be gathered from the bright canary 
yellow of the sulphur, and the sharpness of its crystallization ; 
also from the thickness of the gypsum and its indurated 
condition, traversed by cracks, that in this piece the hydrogen 
* “ Memorie Descrittive, e Descrizione Geologica Dell’Isola di Sicilia di 
L. Baldacci, &c., &c., Roma.” Tipografia Nazionale, 1886, page 286. 
