136 Hidden and Mackintosh—Herderite from Maine. 
The mineral is colorless to faintly yellowish, and is trans- 
‘parent to sub-transparent. Streak white. Crystals very brittle, 
- with fracture small conchoidal. As the form, hardness, — 
streak, color, associations and mode of occurrence were nearly <- 
if not quite the same as those recorded for the rare species 
herderite,* it was concluded that these crystals must belong 
to that species and accordingly tests’ were made to positive 
identify it. specific gravity determination on a : 
quantity gave the result of 8, and on testing for a sepbaae ee 
acid it was found to be present in large quantit 
These results, together with previously obtained erystallo- 
graphic data, seemed to point conclusively to the fact that ib 
was herderite, or a new mineral species. i no quantitative 
analysis of herderite has ever been published and as the gual- 
itative analysis accorded to it was uncertain, we commenced | 
a quantitative analysis of it in order to determine its formula. 
The methods pursued in its analysis were as follows: For the 
determination of phosphoric acid, 300™* were fused with sodium 
carbonate. e fused mass when treated with water ane nitric 
excess 0 oer dissolved in dilute hydrochloric acid The 
residue was fused with sodium carbonate, the silica separated 
Mee 011) = 45° 54’, and 1-443 oe im » 331)= 57°71’. From these the axial ratio 
been calculated @ : 6: c=1: 0°6823:1°6114, The axial ratio pene by Haidin- 
for herderite is 1 : Abed: 15971. ‘ e of the more important angles (supple. 
ment angles) of the Mai se wc da i a with the Seapine angles of 
the original herderite, are as follow = 
% Maine phosphate. Herderite. 
Pad (110% 110) =. 68" 39" 64° 77 
1-i.1-4(101,.101) = 68° 37’ 68° 18’ 3 
14.14(011,01]) = 45° 54’ 46° 2’ Po 
6-% . 6-4 (061 . 061) = 137° 2” 137° 8” 
Gah iee = 38° 46’ 38° 41’ 
043 (001,331) = 67° 27’ 67° 25’ 
These angles show — Seas form of the Maine phosphate approaches closely to 
that as the original herd 2 c 
ae 
a as aay described, is orthorhombic, 7A [= 115° 53’, ONE & 
brittl 
anhyarous phankee <5 eu nag and with fi pn B.B. fuse 
mel with difficulty ; becomes blue wit h cobalt solutio anedeas 
pisedered in muriatic acid. Found very rarely at the tin” mines of Ehrenfri — 
dorf, Saxony (‘also a good topaz locality’).. Resembles the asparagus vat" 
of apatite. (Dana’s Syst. Min., 5th ed., p. 546). 
