STOKES. ] 
MISCELLANEOUS SPECIMENS. 
39 
DR. JULIEN'S SPECIMENS. 
Quantitative composition of Julie it's specimens. 
[The numbers in parentheses are those given in Julien's paper.] 
X u in I KM" 
2H (pyrite I) ... 
29(pyrite96)._. 
30 (pyrite 98) 
31 (pyrite 101).. 
32 (pyrite 106) . 
.'53 (marcasite 1 1 
Locality 
Galena, 111 
Rranklin, N. J - 
Somerville, Mass 
Monroe, Conn _ 
Bastrop, Tex 
j-Cumberland, Eng- 
I land. 
Den- 
sity. 
P. 
5. 015 
60.3 
4.856 
59.0 
t.843 
59.6 
4.819 
60.7 
L791 
67. 7 
| t.987 
42.9 
Composition de- 
duced from p. 
Pyrite 
Pyrite 
.100.0 
. 99.5 
Pyrite 99.5 
Pyrite 100.0 
Pyrite a 100.0 
r Pyrite 83.0 
iMarcasite 17.0 
Composition ac- 
cording to Julien, 
deduced from 
density. 
Much marcasite. 
jPyrite 27.51 
iMarcasite 72. 49 
rPyrite 21.18 
iMarcasite ...78.82 
fPyrite 9.38 
IMarcasite 90. 62 
rPyrite 1.00 
iMarcasite .... 99. 00 
Pyrite 89.45 
Marcasite 10. 55 
a Contains nickel. 
The following descriptions arc in part quoted from Julien's paper: 
No, 28. "Concretionary nodule. Marsden's diggings, Galena, 111. No. 1 (fibrous 
core). Marcasitic pyrite. Very finely fibrous, pale brass-yellow and splendent." 
Analysis (Julien), SiO,. 0.110; Pb, 0.188; As, 0.056. The fracture varies from 
fibrous to prismatic, the prisms being evidently elongated cubes, with termina- 
tions consisting of cube modified by pyritohedron and octahedron. 
No. 2d. "No. 96. Marcasitic pyrite. Franklin, N. J. Sharp, brilliant, brass- 
yellow, striated pyritohedra, yellowish white and splendent on fracture." No 
admixture of marcasite crystals. The value of j) shows that they are practically 
pure pyrite, the low density being probably due to inclosures. 
No. 30. " No. 98. .Marcasitic pyrite. Somerville, Mass. Very sharply defined, 
glittering yellowish cubes, sometimes distorted or rectangular, rarely striated, 
occasionally with octahedral planes upon their solid angles, yellowish white and 
bxilliant on fracture: scattered through a gray argillaceous slate.'' 
No. 31. "No. 101. Pyrite. Monroe. Conn. Deeply striated, distorted, brilliant 
cubes of very pale brass-yellow color, with modifications by the pyritohedron: 
yellowish white, finely granular, and splendent on fracture, and sometimes inclos- 
ing grains of white quartz." 
No. 32. "'No. 106. Marcasitic pyrite. Bastrop, Bastrop County, Tex. Dull 
and pale brass-yellow octahedra, rarely bright, very pale yellowish white and bril- 
liant on fracture; upon black granular crystalline hematite." The specimen con- 
tains a trace of arsenic, a strong trace of copper, and some nickel. It is the latter, 
possibly in eon;] unction with the copper, which causes the high oxidation coefficient. 
No. 33. ''No. 1. Marcasite. Cumberland, England. Hollow incrustation pseu- 
dcmorphs after barite, implanted on a group of barite crystals. The crusts are 
grayish white to tin-white and splendent on fracture, with surfaces drusy with 
pseudo-octahedrons or rhombic pyramids, whose smooth, rectangular terminal faces 
(the basal pinacoid OP) project but slightly; a few minute rhombic prisms also 
occur, and some hexagonal though apparently triangular twins." The supposed 
rhombic pyramids with basis are evidently combinations of cube and octahedron 
belonging to the 83 per cent of pyrite which it contains. 
DISCUSSION OF JULIEN'S HYPOTHESIS. 
The above list includes some of the most pronounced cases of "marca- 
sitic pyrite " described by Julien — that is, material with the crystalline 
