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£. 8. Dana—Herderite from Maine. 229 
Arr. XXVIII.—On the Crystalline Form of the supposed 
Hlerderite from Stoneham, Maine ; by Epwarp 8S. Dana. 
. 
Messrs. Hidden and Mackintosh have described a mineral from 
Stoneham, Maine, which, as they show, is probably identical 
with Haidinger’s herderite. The first notice of this mineral 
was given by Mr. Hidden in the January number (p. 73). Mr. 
Hidden has had the kindness to place in my hands the best of 
his specimens for crystallographic description, and I have also 
to thank Mr. George F. Kunz, of New York, for additional 
material furnished me for the same object. The study of 
these specimens has enabled me to make out the form of the 
mineral with reasonable accuracy. ; 
he crystals examined were mostly quite small, varying 
from 1 or 2 to 3™ in diameter, though there were also a ie 
larger crystals, A preliminary examination served to confirm 
the results of Mr. Hidden that the form of the Maine mineral 
approximated closely to that of the herderite from Saxony. 
Ae position in which the crystals are placed is consequently 
- Made to correspond with that of the herderite as given by 
Brooke and Miller (p. 490) and in Dana’s System of Mineralogy 
+ p. 546).* The measurements and the optical examina- 
wal §0 to prove that the crystals belong to the orthorhombic 
stem. 
In the preceding number of this Journal (III, XXvil, rites 
The crystals are prismatically developed in the direction of 
the brachydiagonal axis, as shown in the figures (1, 2, 3), and 
ey are ordinarily terminated at both extremities of this axis. 
The commoner forms are those of figures 1 and 2, the habit 
varying according to the development of the pinacoids 4 and c. 
Occasionally more complex forms, as that in figure 3, are seen, 
and in one or two cases the erystals were farther modified by 
Several minute planes not. there represented ; these are J, n, ¢ 
(see below), and two or three others which could not be deter- 
Mined with certainty. 
The observed planes are fifteen in number, viz: 
9 (001, c), 4-4 (010, 5); prisms J(110), «2 (120, Y), #-3 (130, m); macrodome 
#7 (302, 9); brachydomes 1-% (011, u), 3-€ (032, #), 3-4 (031, v), 6-4 (061, 8); PyTa- 
mids 1 (111, p), § (882, g), 3 (331, n); 3-3 (362, a); 3-3 (131, ye 
Considerable difficulty was found in obtaining satisfactory 
fundamen 
* By Haidinger, and after him Naumann, t=¢-} (230), and J=}-1 (032). | 
tal angles, and a large number of measurements were = 
