GEOLOGY AND MINERALOGY. 325 



the name of haoutle. This substance was formerly considered to be a kind of 

 marl or earth; and probably the greater number of the so-called "edible earths" 

 of Central and South America are of an analogous composition. 



MINERALOGICAL NOTICES. 



Tetradymite {Telluric Bismuth.) — Dr. C. T. Jackson (Silliman's Journal, May, 

 1859) announces the occurrence of Tetradymite in Field's gold mine, Dahlonega, 

 Georgia. It occurs in thick foliated masses, associated with native gold and 

 auriferous iron pyrites in a quartz vein traversing hornblende slate. Color, steel- 

 grey. Flexible, sectile, and soiling the fingers like graphite. H=2-25 ; Sp. gr. 

 'Z-SeS. One gramme yielded : Bismuth 0-'7988 ; Tellurium 0-1800 ; Selenium 0-0118 

 Gold ("mechanically mixed) 0-0060 ; Loss 00114. 



Alisonite. — Under this name F. Field describes in the May number of Silliman's, 

 Journal, a ne-w species (?) from the Mina Grande near Coquimbo, Chili. Color ; 

 indigo-blue. Massive, with conchoidal fracture. H=2-5 — 3 ; Sp. gr. 6'10. Oompo- 

 sition=Copper53'63; Lead 28.25; Sulphur IT. 00: corresponding to 3 Cu^S,? bS. 

 Plattner's Cupro-Plumhite also from Chili, gives Cu-S, 2PbS. Mr. Field states, 

 further, that the substance formerly described by him as new, under the name of 

 Guaycanite (Sill. Jour. vol. xxvii, p. 52) proves to be the rare Enargite (Breit- 

 haupt.) 



Boltonite. — Professor George J. Brush, in the above mentioned number of Silli' 

 man's Journal, has shewn in support of the views of Professor J. Lawrence Smith 

 and in opposition to those of Kengott, that the Boltonite of Shephard, from Massa- 

 chussetts, &c., is really identical in composition with Chrysolite: the combined 

 MgO and FeO of ordinary chrysolite being represented in Boltonite by MgO alone. 

 An analysis of a pure specimen, furnished by Prof. Shephard, afforded Prof. Brush 

 the formula 3 MgO, SiO^ 



Saussurite. — Professor T. Sterry Hunt in an elaborate paper (also in the May 

 number of Silliman's Journal) on Euphotide and Saussurite, has determined the 

 latter substance, long considered an impure feldspar, to be a zoizite or " lime- 

 alumina epidote "; or, at least, to be closely related to that species. The Saussurite 

 analysed by Mr. Hunt was presented to him by Prof. Guyot. It formed a portion 

 of the Euphotides of Mt. Rose, on which the original descriptions of de Saussure 

 and Haiiy were founded. The analyses show the oxygen ratios of the protoxides, 

 peroxides and silica, to be nearly as 1 : 2:3, yielding the epidotic formula (as 

 commonly received) 3 E.0, 810^ + 2 (R^O^, SiO^.) The following are the principal 

 physical characters, according to Mr. Hunt : — Massive and very tough, with fine 

 granular or compact structui-e, and sub-conchoidal or splintery fracture. Color, 

 white, passing into greenish, bluish, and yellowish-white, rarely with flesh-red 

 stains. Sub-translucent, with feeble, waxy lustre. H='7*0 (scratches quartz.) 

 Sp. gr. 3-33 — 3'38. These characters coupled with Mr. Hunt's analyses, incline 

 us in the present state of the question to look upon Saussurite as an epidote some- 

 what altered physically by prolonged metamorphic action, i-ather than as a distinct 

 species. The blow-pipe comportment is not stated, but it would be interesting to 

 ascertain it, as in the epidotes, both per se and with the ordinary reagents, the 



