MINERALOGY. 701 



Other analyses of ditfereiit samples gave concordant results, all agree- 

 ing with theformulaMgB204 4-3H20, which requires: B2O34209, MgO 

 24-39, H2O 3292. 



Polyarsenite-Sarkinite. — These are two minerals described independ- 

 ently by different authors, from diflerent localities, and yet very closely 

 related, if not identical. Polyarsenite, named by Igelstrom in allusion 

 tp its large amount of arsenic, is from the Sjo mines in the Grythyt- 

 tan parish, Sweden. It has a yellowish-red color, is transparent, but 

 shows no crystalline form and no cleavage ; an optical examination by 

 Bertrand shows that it is biaxial, with an angle of 83^ and a negativ^e 

 bisectrix ; specific gravity 4-085. It is found in granular form, associated 

 with a little barite, and also hematostibiite in veins in calcite embedded 

 in tephroite. An analysis by Soderbaum is given below. 



SarMnite, named by A. Sjogren from (rdpxtvog (bloody, fat), with a 

 double allusion to its blood-red color and greasy luster, is from the iron- 

 manganese mines of Pajsberg, Sweden. Its hardness is 4 to 5, and 

 specific gravity 4-14. Two cleavages were observed, but no crystals 

 were found, and the system is thus in doubt; optically, however, it is 

 biaxial. An analysis was made by C. H. Lundstrom, and for the sate 

 of comparison it is placed beside that of polyarsenite. 



A82O5 SbsOs PaOg MnO FeO CaO MgO H2O 

 Polyarsenite (S) . 39-05 1-20 .... 50-18 tr. 2-88 0-75 3-15 CO2 3 -51 = 100-72 

 Saikinite 41-60 ... 0-21 51-60 0-13 1-40 0-98 3-06 insol. 0-38, PbO 0-25, CO? 0-76 = 100-37 



For the former Cleve calculates 4MnO, AS2O5 + H2O, which requires: 

 AS2O5 43-23, MnO 53-38, H2O 3-39 = 100. 



Uiiitahite — This name has been given by W. P. Blake to a peculiar 

 variety of asphaltum which occurs in considerable quantities in the 

 Uintah Mountains. It is obtained in masses several inches in diameter ; 

 it breaks with a conchoidal fracture, is brittle and easily reduced to 

 powder in a mortar. The hardness is 2 to 2-5, and the specific gravity 

 1-065 to 1-070. The color is black and the surface brilliant and lustrous. 

 It fuses easily in the flame of a candle and burns with a brilliant flame, 

 resembling sealing-wax, and like this it gives a clean, sharp impression 

 with a seal. It gives off upon distillation a small quantity of a clear 

 white dense oil and a little vapor. It is soluble in heavy lubricating 

 petroleum, while the lighter i)roducts of the petroleum do not affect it. 

 It is soluble also in warm oil of turpentine, but not in ordinary alcohol^ 

 and in ether only when powdered. In melted wax it dissolves, forming 

 on cooling a hard black mixture resembling " burnt wax." It is sug-^ 

 gested that it may prove to be useful in various ways in the arts. A 

 more complete chemical examination is needed to establish its true 

 character. 



