258 A. J. Moses — New Mercury Minerals from Texas. 



Chemical Analyses of Terlinguaite. — Analyses I, II and III 

 were made by Mr. McCord by fusion with soda in a closed 

 tube as described under eglestonite. Analysis lY was made 

 to determine the loss by heating. All samples were separately 

 picked. The results tabulate as follows : 



I II III IV 



Grams taken -_ _ -1960 -1078 -0874 -06635 



Percent oxygen 3*47 



" chlorine ._ 7-78 . 800 



" mercury.. 88-67 87-38 88-64 



These determinations lead to the simple empirical formula 

 of Hg^ClO as follows : 



Percentages Percentages Group 



in Hg2C10. by analysis. proportions. 



O 3-544 3-47-^ 15-88 =: -2185 or -974 



CI 7-852 7-89 -f- 35-18 = '2242 '' I'OOO 



Hg 88-604 88-24 -^ 198 49 = -4445 '' 1-983 



100-000 99-60 



Other characters of Terlinguaite. — Luster, brilliant adaman- 

 tine. Color, sulphur-yellow with a slightly greenish tinge, 

 very slowly darkening on exposure to an olive green. Color 

 of powder lemon-yellow, also slowly becoming olive-green. 

 Transparent or nearly so. Hardness between 2 and 3. Brittle- 

 or sub-sectile. 



Specific gravity on very carefully picked samples 8*725, 

 higher than eglestonite by 0'316. 



Quantity taken '4443 -4545 



Weight in water _. . -3934 -4024 



Specific gravity 8-728 8-723 



Between crossed nicols there is distinct double refraction. 

 The crystals can be viewed only normal to the 1) axis and show 

 extinction parallel to this. 



Heated on charcoal and in the closed tube, behaves like 

 eglestonite except that a little oxide appears to be formed, giv- 

 ing a pinkish tinge to the white sublimate. 



In nitric acid behaves like eglestonite but dissolves more 

 rapidly. In hydrochloric acid becomes white but does not 

 appear to dissolve. 



jDistinctioJis from Eglestonite. — The most convenient dis- 

 tinctions are the yellow color and the very slow change of color 

 to olive-green as compared to the brownish color and rapid 

 change to black with eglestonite. The eglestonite crystals are 

 usually easily recognized. In testing, the doul)le refraction 

 and the more rapid solution of the terlinguaite are characteristic. 



