Geplogy and Mineralogy. 305 



of the experiments do not altogether agree with previously pub- 

 lished views. The author finds that " the silver has not accumu- 

 lated, but on the contrary decreased ; the scale, however, contains 

 a larger amount of gold. The increase of gold in the scale may 

 be due to the deposition of gold from the sea-water on to the sur- 

 face of the metal, or it may be due to the comparative non-solu- 

 bility of gold in sea-water ; the muntz naetal having been corroded 

 and dissolved away, together with much of the silver, leaving the 

 gold behind." He believes that it is " probably due to both 

 causes, i, e., partly to deposition and partly to accumulation, for 

 the superficial parts of certain of the experimental plates obtained 

 by scraping them, show an increase in the amount of gold and a 

 decrease in the amount of silver; the increase in the gold cannot 

 in these cases well be due to mere accumulation, since the plates 

 do not appear to have lost sufficient weight to materially increase 

 the proportion of the residual gold." 



Y. Brief notices of some recently described minerals. — Rathite, 

 named by Baumhauer after Gerhard vom Rath, is a new mineral 

 from the dolomite of the Binnenthal, a region to which the hon- 

 ored German mineralogist devoted much study. It occurs in 

 slender needle-like crystals belonging to the orthorhombic sys- 

 tem ; these have a prismatic development parallel to the macro- 

 diagonal axis with fine striations and approximate to dufrenoysite 

 in angle ; they are in part twins. It resembles dufrenoysite in 

 color and luster. An analysis by A. Bomer gave : 



S As Sb Pb Fe 



23-72 ]7-24 4-53 52*98 0-56=:99-03 



The exact formula remains in doubt. — Zeitschr. Kryst., xxvi, 593, 

 1896. 



Salvadorite is a new copper-iron vitriol from the Salvador 

 mine, Quatena, Chili. It occurs as a crystalline aggregate of a 

 bluish green color. Analyses of two kinds gave : 



SO3 CuO FeO H2O 



Green 27-87 18-77 8-49 44-65 = 99-78 



Blue 28-16 17-57 9*59 44-31 = 99-63 



For these the formula, FeCu.^(SOj3 + 2lH20 is calculated. This 

 brings it near pisanite, from which, however, it differs in optical 

 characters. Described by W. Herz in Zeitschr. Kryst., xxvi, 16, 

 1896. 



Caswellite, named after John H. Caswell of New York, is an 

 altered biotite from Franklin Furnace, New Jersey. It has a 

 copper-red or flesh color, resembling a light-colored clintonite; 

 hardness 2-5-3 ; specific gravity 3-54. It retains the cleavage 

 but has lost the elasticity ot the original mineral. It is associated 

 with massive yellow garnet and rhodonite. An analysis gave : 



SO2 FeaOs AI2O3 MnaOs CaO MgO ign. 

 I 38-74 6-85 6*58 15-95 22-30 5-52 4-64 = 100-58 



Described by A. H. Chester in the Aiin. Rep. State Geologist of 

 New Jersey ior 1895. 



