Chemical Examination of Algerite. 119 
deep brownish-yellow, which is evidently due to their partial 
decomposition. Those found at the depth of twelve inches 
or more, are yellowish-white or straw-yellow, sometimes with 
a greenish shade ; in a few instances I have found them per- 
fectly colorless and possessing a good degree of translucency. 
Even the dark yellow crystals, when not decomposing, are 
slightly translucent, and they then bear a striking resemblance 
to chondrodite, with which the mineral, when first obtained in 
a few fragments, was supposed to be identical. It has also 
been referred to scapolite and spodumene, but it differs from 
both of these in form and hardness, as well as in other essen- 
tial characters. In fact its hardness is even inferior to that 
of laumonite in fresh crystals. 
* I believe that Prof. Nuttall was the first mineralogist who 
expressed the opinion that this mineral might prove to be a 
new species, but I am not aware that he ever entered into 
any investigation of its character to satisfy himself upon this 
point, and for the last ten years, it appears to have been en- 
tirely overlooked, the locality even not having come under the 
cognizance of any mineralogist since his visit to it, until re- 
cently explored by myself. "The crystals are rhombic prisms 
the faces M and M' inclining to each other at an angle of about 
94°, as determined by the common goniometer. In no case 
have I found an individual, having distinct terminal or basal 
planes by which to determine the angle of P on M, but an 
oblique termination of the prism is clearly indicated both by 
its natural joints and cleavage, so that we have an oblique 
thombic prism as the primary form; the accurate measure- 
ments of which further examination must determine. None 
of the faces are sufficiently brilliant for the reflecting goniom- 
eter, although the imperfect cleavage surfaces which may be 
obtained, parallel with the lateral planes of the prism, some- 
times possess considerable lustre; they present a pearly re- 
flection in spots, the prevailing lustre being vitreous. In its 
general aspect, when taken from near the surface, the mineral 
would be described as without lustre and transparency. 
