48 W. T. Schaller — Natramblygonite, a New Mineral. 



Art. VI. — Natramblygonite, a New Mineral; by 

 Waldemae T. Sohallek. 



Natbamblygonite is, as the name indicates, a soda ambly- 

 gouite, or a hydrofluo-pkosphate of alumina and soda, with the 

 soda in part replaced by lithia. 



Occurrence. — The new mineral described in this paper was 

 collected by me in 1908 in a large pegmatite mass four miles 

 northwest of Canon City, Colorado. The presence of lithia 

 minerals — lepidolite and pink tourmaline — had been noted in 

 this pegmatite by Sterrett,* and it is owing to his favor and 

 kindness, as well as to that of Mr. J. D. Endicott of Canon 

 City that I was enabled to visit the locality and collect a suite 

 of specimens from the pegmatite. As described by Sterrett, 

 the occurrence of the tourmaline and associated minerals is on 

 a low oval hill composed of pegmatite inclosed in contorted 

 biotite and hornblende gneiss. Pink tonrmaline and lepido- 

 lite are abundant though no cavities or pockets affording gem 

 tourmaline were seen, the mineral being found only in the 

 solid pegmatite. 



Association. — The minerals associated with natramblygonite 

 are few in number and do not possess any unusual properties. 

 Tourmaline is abundant in black, pink or green crystals 

 though no faces except those in the prism zone were seen on 

 any of the crystals collected. A dark green, nearly black core 

 with a pink shell seems to be a common color association for 

 this locality. Small masses of minute bluish crystals and some 

 larger green ones imbedded in muscovite were also noted. 

 Most of the tourmaline is opaque and partly altered. The 

 micas, muscovite and lepidolite, are also abundant. Lepidolite 

 occurs in scaly pink masses, also as larger plates and in indefi- 

 nite crystalline aggregates of pink or purplish colors. Albite 

 generally is tabular in platy masses or in groupings of small 

 crystals. The quartz and potash feldspars are massive and 

 the single piece of natramblygonite found is also massive. 



Description of nevj mineral. — The specimen of the new 

 mineral measures about 7x5x3 cms and consists of a mass of 

 cleavable natramblygonite surrounded by feldspar and lepido- 

 lite. Small veins and isolated masses of lepidolite are found 

 scattered through the new mineral. Small amounts of pink 

 tourmaline and of albite were also detected imbedded therein. 



Three directions of cleavage can be detected, one more 

 prominent than the other two. A section of the mineral cut 

 parallel to the most prominent cleavage showed the other two 



* Sterrett, D. B. The Production of Precious Stones in 1908; Mineral 

 Eesourees 1908, U. S. Geol. Survey, 1909, p. 44. 



