152 



W. T. Schaller — Miner alogical Notes. 



Art. XIV. — Miner alogical Notes ; by Waldemar T. 



Schaller.* 



1. Purpurite from two new Localities. 



2. Manganotantalite from Mt. Apatite, Maine. 



3. Evansite from two American Localities. 



4. Tourmaline from Elba. 



5. Zinnwaldite from Alaska. 



6. Forms of Pisanite — a correction. 



1. Purpurite from Two New Localities. 

 South Dakota. — Some specimens of ore found near Hill 

 City, S. Dak., were seen to contain a considerable amount of 

 purpurite,! and through the courtesy of Mr. J. 1ST. Smith, who 

 sent in the first specimens, a larger quantity of' material was 

 obtained. Almost all the fresh cleavage surfaces of the black 

 iron-manganese phosphate which chiefly forms the ore are 

 covered with a film of purpurite. On breaking the black phos- 

 phate transverse to the cleavage but little purpurite is seen, 

 and it seems probable that the latter is formed from the black 

 mineral. 



The properties of the mineral as seen under the microscope 

 agree with those determined on the original mineral (from North 

 Carolina). One small piece showing crystal outline was noticed, 

 and is shown in the accompanying sketch (fig. 1). The extinc- 

 tion is parallel and the pleochroism is 

 as follows : Parallel to the cleavage lines 

 (vertical direction), rose-red ; normal to 

 the cleavage lines, blue purple. The 

 absorption parallel to the cleavage lines 

 (rose-red) is less than at right angles to 

 this direction. On account of the fre- 

 quent occurrence of small platy masses 

 showing cleavage lines, the mineral has 

 probably two cleavages at right angles 

 to each other, one more perfect than 

 the other. It is probably the imperfect 

 one which is normal to the figure and 

 whose traces show in the vertical lines. 

 On account of the larger quantity of 

 material, a determination of the density was made, the value 

 previously given being unsatisfactory. The material was broken 

 into small pieces and the fragments of purpurite picked out. 

 The final sample was not pure, as a small amount of the black 

 substance could not be separated. The density determination 

 was made by weighing the mineral in water in a small test tube 



* Published by permission of the Director of the XJ. S. Geological Survey, 

 f This Journal (4), xx, 146, 1905. 



