Hidden — Mineral Research in Llano County, Texas. 429 



Only the density of nivenite saved it from being thrown away 

 as magnetite (very abundant at this mine), and but for its asso- 

 ciations it would be always neglected except by the expert 

 mineralogist. Equally so with the mackintoshite, its resem- 

 blance to the dark cyrtolite and intimate association with it, 

 prevents it from being recognized by the miner or layman. 

 Some day this mine promises to be worked for the two last- 

 named minerals alone and as the main object of mining there, 

 and in the deeper working they should be found abundantly 

 and in a higher state of purity. 



Tengerite ( ? ) — About ten grams of a white mineral, occur- 

 ring in semi-globular and flat radiated concretions in the cracks 

 and fissures of the gadolinite, were finally obtained after much 

 labor and search. This quantity was the result of detaching 

 the mineral, bit by bit, from over 300 kilos, of fresh gadolinite. 

 Since the composition of tengerite (to which species this sub- 

 stance is tentatively referred) is unknown, I submitted the rare 

 mineral to Dr. W. F. Hillebrand of the U. S. Geol. Survey 

 for analysis ; his report is given in full below. The surpris- 

 ing feature is the presence of glucina (BeO) in the form of 

 carbonate, which is new to science, and this may perhaps indi- 

 cate a new glucinum mineral mechanically mixed with a basic 

 hydrous carbonate of the rare earths of the yttrium group. 



Dr. HillebraiuVs Report and Analysis. 



" The purest material that could be picked out, from that at my 

 disposal, showed some brown admixture with the white. The 

 following results were obtained from *3640 gram of this selected 

 material, after deducting -0262 gram of residue, left after long 

 treatment of the ignited powder with cold and quite dilute nitric 

 acid. 



Y 2 3 group 40-8 per cent Mol. wt _ . 226 



Ce 2 3 group 7*0 " " " 335 



Fe 2 3 4-0 



BeO (GIO) 9-7 



CO, 19-6 



H 2 above 105°_ 14-1 



H 2 below 105°. 3-2 



Si0 2 -4 



MgO, Alk., loss . 1-2 " 



100-0 



All determinations were made on the one portion, the C0 2 and 

 H 2 being directly and simultaneously ascertained by ignition in 

 a tube and collection of the escaping gases. The loss in weight 



