GI>S aCIENTIl £C KECOKl) FOR 1885. 



80iue rather obscure isometric crystals, but generally i" a compact ir- 

 regular mass, uearly colorless and isotropic. x\n imperfect analysis 

 gave the following results : 



F Al Ca Mg K Na 



46-98 11-32 0-72 0-22 28-94 9-90r^98-08 



Tlie alkalies were determined approximntely only, and lieuce no at- 

 tempt is made to calculate a formula, but it is suggested that it may be 

 regarded as a cryolite, in which two-thirds of the sodium are replaced 

 by potassium. Further investigation is to be desired. The name is 

 from the county El Paso, which embraces the greater part of the Pike's 

 Peak region. 



Endlichite.— Among the specimens from the newly-described locality 

 of descloizite, in Lake Valley, New Mexico, was a vandiferous mimetite 

 to which Dr. Genth has given the name Endlichite (after Dr. F. M. End- 

 lich). Like the related isomorphous species, mimetite, vanadiuite, and 

 }>yromorphite, it occurs in hexagonal prismatic crystals. These are mod- 

 ified by pyramidal planes, both being strongly striated. The crystals are 

 also sometimes hollow. An analysis was first made (1) of crystals of a 

 yellowish-white or pale straw-yellow color, the largest 'i^'^ long and 0-5 

 to l-S™"" thick, A second analysis was later made (11) of the same rain- 

 eral, occurring in groups of crystals having a columnar structure. The 

 color varied from white to yellowish-white, straw yellow, and at the ex- 

 tremities sometimes changing to deep orange red. The largest groups 

 were 10™°^ in length. The analyses were as follows : The material upon 

 which the first was made consisted largely of impurity (76.4 per cent, 

 quartz, &c.). 



AS206 VaOs Pb O CI 



1 10-73 7-94 79-15 2-18 = 100 



II(sp.^'r;iv.= 0.864) 13-52 10-98 7348 2-45 CaO 0-34, P2O5 tr. = 100-77 



The calculated formula is PbsCl (As04)3 + PbsCl (¥©4)3, which re- 

 quires: AS2O5 11-86, V2O5 9-60, PbO 68-99, Pb 7.11, CI 2 44=100. 



Gerhardtite. — A new copper mineral, unique in that it is the only 

 nitrate thus far known in nature, except the soluble nitrates of sodium, 

 magnesium, &c.; it is described by H. L. Wells and S. L. Peufield. 

 Only a single specimen has as yet been identified ; this was from the 

 United Verde copper mines, Jerome, Ariz., and consisted of pure mas- 

 sive cuprite, inclosing in a crack the crystals of gerhardtite and a few 

 acicular crystals of malachite. The crystals belong to the orthorhombic 

 system; they are pyramidal in habit, consisting of a zone of nine pyra- 

 mids in oscillatory combination with the basal ])l;ine predominating, and 

 the prism and a macrodome subordinate. There is a perfec basal 

 cleavage and also a second cleavage parallel the macropinacoid. The 

 mineral is very soft (hardness=2) and cleavage plates can be readily 

 bent, then separating in the direction of the second cleavage. The 

 specific gravity is 3-426. . The color is dark green and the streak light 



