F. A. Genth — Contributions to Mineralogy. 199 



seven to eleven pounds. I am indebted to Mr. W. Earl 

 Hidden for some from Llano County, Texas, and give in the 

 following the results of my analyses of this, as well as that 

 received from Dr. Foote. 



It has a black color ; in thin splinters it is translucent with a 

 dark bottle-green color ; the fine powder is greenish-gray ; 

 fracture conchoidal to splintery. Sp. gr. =4*201 (Burnett Co.) 

 to 4'254 (Llano Co.). Heated to low redness, it begins at once 

 to glow vividly through the whole mass and swells up into 

 ragged fragments of a grayish- white color, only superficially 

 melted. The fine powder is soluble in dilute acids, even after 

 ignition. The best solvent I found to be dilute sulphuric acid 

 (1 : 20) in which it dissolves in the cold after repeated shaking, 

 leaving only a minute, somewhat flocculent, reddish residue of 

 ferric oxide and a little quartz which were mechanically mixed 

 with the gadolinite. 



The Texas gadolinite is altered into a brownish-red mineral 

 of waxy luster, finally into a reddish or yellowish-brown 

 earthy substance. Neither could be obtained in a state of 

 purity, but I will give below a partial analysis of the former. 

 Tengerite (?) or yttrium carbonate in thin, white crystalline 

 incrustations is found between the cracks of the gadolinite. 

 There was only enough obtainable to show their composition by 

 qualitative tests. 



In the analyses of the Burnett Co. gadolinite I, a and b, it 

 was dissolved in hydrochloric acid, in those of the Llano Co. 

 mineral II, a and b, in dilute sulphuric acid and the mechan- 

 ically admixed ferric oxide and silica separated by filtration. 

 The other separations were made in the usual manner. The 

 cerium oxide was separated from the oxides of didymium 

 and lanthanum by oxydizing the almost neutral nitric acid 

 solution with bromine, and precipitation of the boiling solution 

 with sodium acetate. This was repeated five times, when, 

 finally, the filtrate gave only traces of oxides which could be 

 precipitated with oxalic acid and the eerie oxide showed a pale 

 salmon color. The oxides, separated from the cerium were 

 chiefly didymium oxide, and lanthana in smaller quantity. 

 The oxides of the metals of the yttrium group gave almost 

 white salts, with only a very faint rose color of that of erbium. 

 The separation of glucina and alumina from ferric oxide was 

 effected from a solution of citric acid and ammonia by precip- 

 itating the iron as ferrous sulphide, which method 1 found to 

 give the most satisfactory results. The little alumina was 

 separated from the glucina by precipitating the nearly neutral 

 solution and re-dissolving the precipitate in a strong solution 

 of sodium hydrate and, after the dilution with much water, 

 precipitating the glucina by continuous boiling. After acidu- 



