‘of cubic gold, while he cites examples of the octahedron; andy 
* 
. the contrary, for he says (Min. Ed. by Haidinger) they are ofter 
3 Se z oh . 
= te | 
104 .. B Alger’ on » Critic 4 Collie. 
viz., the eutablishiing of | a cube as ‘the primary forts of mineré 
which have never been known to occur under such form si 
which even present a‘distinct octahedral cleavage... “This i is “eH 
case with two at least.’ If we take the simple rm, the. cv es 
should be made the primary of native iron, copper, lead, silvery 
and mercury; aud so of some others, which ocdur. in octa hei 
drons. and are not determined ‘ any certain cle e. In the 
case of copper, some authors have made the cee primary. 
Haiiy (Traité, 1808) even expressed his doubts as to the existence! 
Beudant, (Min., 1832,) says they are very rare.t Mohs implies 
hollow, while the octahedrons are smooth. Cleaveland describes’ 
the crystals in general as small and imperfect, and Nicol, im his ~ 
late work, in the like manner, observes, “ they are small and very © 
small.” I hope we may yet say of our California gold crystals, 
they are large and very large, as much for the benefit of miner- * 
alogists, as a reward to the industry and hard toil of the diggers. — 
Crystals of rare modifications.—Among the specimens col- 
lected by Mr. Tyler, I have found several: rare thodifieationsaieg 
this metal, such as come to us in their most perfect forms from + 
Brazil. I here give oon. of two of them. One, fig. 1, (a, b,é,) 
al 
represents a compound form produced by the union of two op- , - 
posite sections, or segments, of an emarginated octahedron; 4 
form not unfrequently presented by octahedral spinelle. ‘The 
other, fig. 2, has the apparent form of irregular six-sided tables, 
with truncated edges, and isa modification of the same form. 
They are tolerably well represented by the figures referred to, 
but the planes of the dodecahedron (e) are less conspicuously de- 
fined on the real crystals, owing to their extreme thinness, and 
— edges being rounded off, or otherwise disfigured. For this J 
ee 
* They differ in cee to silver and iron, some adopting the cube, and*bthers the 
wt Gros as the Lprans 
Cronstedt, in A sirarslonrs. says, “I have procured in Transylvania a specimen 
of cubic native gold, but I have never seen it any where else.” In ore enumer- 
ation of ps splendid Turner collection formed by of the Heuland, examples 
are given of the regular octahedron, and only two of cube, one these being 
from the very locality Cronstedt speaks of. 
