426 Hidden — Mineral Research in Llano County, Texas. 



Among the most notable discoveries of " Barringer-Hill " 

 minerals, at this time, were the double crystal of gadolinite 

 that weighed seventy-three pounds and an eighteen-pound mass 

 of yttrialite (see figures 1, 2 and 3) ; a mass of pure allanite 

 that weighed over three hundred pounds ; about fifty pounds 

 of thoro-gummite, among which were pieces weighing fully a 

 pound and some few good crystals. Of fergusonite several 

 very pure masses and large aggregations of rough crystals were 

 found, up to five pounds in weight. Of rowlandite one very 

 pure mass weighing just one kilo was obtained ; of nivenite 

 and mackintoshite very little was discovered. The mineral 



species rich in yttrium-erbium were more particularly sought 

 after because thorium and uranium were not used in the 

 " glower " of the Nernst Lamp. 



Masses of coarsely crystallized fluorite up to four hundred 

 pounds weight were not rare, and some of these had very large 

 faces of the cube and rhombic dodecahedron. Its color varied 

 from dark green to |3uce and purple, and colorless transparent 

 rough crystals having remarkably perfect cleavage were some- 

 times observed. Some of the fluorite was true chlorophane 

 and exhibited a brilliant green light when strongly heated and 

 viewed in the dark. One mass was self-luminous, at night, 



