MINERALOGY. 457 



The element germonium is allied to arsenic and antimony, and lias an 

 atomic weight of 72.3 and a specific gravity of 4.7. The formula of the 

 mineral is written 3Ag2S . GeSz . 



Arnimite. — Described by Weisbach as a new hydrous sulphate of cop- 

 per. It was found on the porcelain jasper of Planitz, near Zwickau, 

 where it has been formed in the course of the burning of a bed of coal. 

 It forms a green coating, which, under the microscope, is resolved into 

 short needles or scales. Several analyses were made by Winkler, but 

 the material was more or less impure, with gypsum, anhydrite, etc. 

 Moreover, the assumption was made that the loss of 17 per cent, was 

 to be taken as water. It is evident, therefore, that the composition set- 

 tled upon is more or less uncertain, namely, CU5S2OU + CH2O. This 

 requires : 



SO3 CuO H,0 



24.07 59.69 16.'24 =99.81 



This mineral seems to be most nearly allied to herrengrundite, and 

 Weisbach suggests that the latter may be considered a calcium variety 

 of arnimite. The name arnimite is given in honor of the von Arnim 

 family, who for centuries have owned the Planitz coal works. 



Arscnolamprite. — Named by Hintze as an independent form of metallic 

 arsenic. The specimens under examination were from Chili. Tiiey cor- 

 responded in characters with the arsenglanz from Marienberg, long since 

 described by Breithaupt, and by him also called hypotyphite. Frenzel, in 

 1874, examined the Saxon mineral, and arrived at the conclusion that it 

 was probably a distinct species. The specific gravit}^ is 5.3 to 5.5, or 

 decidedly lower than that of ordinary arsenic (5.7 to 5.8); the hardness 

 is also less. The luster is brilliant metallic, the color lead-gray with a 

 tinge of blue, the streak black. The structure is foliated with distinct 

 cleavage in one direction. An analysis yielded 98 per cent, arsenic, 

 with small quantities of iron and silica in addition. 



Brniachite. — A name given by Macadam to a mineral found at Loch 

 Bruithaich, Scotland, incrusting barite. It is stated to be clear, beau- 

 tifully crystalline, with a tendency to a bluish tinge of color and very 

 friable. It was mentioned by A. Wallace in a brief description of the 

 Bruithaich locality. An analysis gave: 



F CaO NaaO Fe^Os Si02 



10.01 87.04 1.70 0.59 0.54 = 99.88 



A further examination is needed. 



CaracoJite. — Described by Websky as an osychloride of copper with 

 sodium sulphate from Caracoles, Chili. It occurs intimately associated 

 with the rare mineral percylite in colorless crystals aggregated in crusts. 

 The crystalline form is made out to be orthorhombic, witli pseudohexag- 

 onal symmetry due to twinning. It appears in obtuse hexagonal pyra- 

 mids, with prism associated. By an examination in jiolarized light the 



