106 Rogers — Lorandite from the Rambler Mine, Wyoming. 



the cleavage faces, but the prism faces {110 \ are dull. Even 

 if bright they could not be measured on account of the close 

 proximity of the matrix. 



Fragments are prismatic, non-pleochroic, and have parallel 

 extinction. Lorandite is monoclinic, but the cleavages are in 

 the zone of the ortho-axis and so have parallel extinction. 



On charcoal lorandite fuses easily to a black globule, color- 

 ing the flame bright green. It gives a green flame when fused 

 on platinum wire and alloys with the platinum. In the closed 

 tube it fuses to black globules, giving a black and red subli- 

 mate and also minute colorless adamantine crystals of As 2 8 . 



The lorandite is soluble in nitric acid, turning yellow. With 

 chloroplatinic acid the solution gives a light yellow precipitate 

 (Tl 2 PtCl 6 ). After evaporating off the nitric acid, potassium 

 iodide gives a yellow precipitate (Til). The nitric acid solu- 

 tion with hydrochloric acid gives a white precipitate (T1C1). 



With the spectroscope this white precipitate of thallium 

 chloride gave a single bright line in the green. With a pure 

 thallium salt the green line appeared at exactly the same 

 position. 



Although the blowpipe and chemical tests were made with 

 a very limited amount of material consisting of minute 

 detached fragments, the identity of the mineral with lorandite 

 is well established. The spectroscope proves it to be a thallium 

 mineral and the goniometrical measurements prove it to have 

 the crystal form of lorandite. The blowpipe and chemical 

 tests are confirmatory. 



Stanford University, California, 

 Oct. 1911. 



