394 S. L. Penfield — Anthophyllite from Franklin, N. C. 



gen be a constituent of other species in a form hitherto unsus- 

 pected and unrecognizable by our ordinary chemical manipu- 

 lations ? And if so, other problems are suggested which it is. 

 not now in order to discuss. rff»' 



Laboratory of the U. S. Geological Survey, 

 Washington, D. C, June 30th. 



, ; r, ■' 



Art. L. — Anthophyllite from Franklin, Macon Co., N. C. /• 

 by S. L. Penfield. 



As an orthorhombic member of the hornblende group of 

 minerals anthophyllite is of special interest, being a magnesia- 

 iron silicate without calcium, and standing thus in the same 

 relation to hornblende as the orthorhombic enstatite, bronzite 

 and hypersthene do to the monoclinic pyroxene. As far as the 

 author can learn it has never been fully identified from any 

 locality in the United States. Many specimens which may be 

 seen in collections labeled anthophyllite will be found, when 

 examined with the microscope, to be fine fibrous or radiated 

 varieties of hornblende. The material which will be described 

 in the present paper was collected at the dump of the Jenks 

 Corundum Mine, Franklin, Macon Co., 1ST. C, by Mr. Norman 

 Spang, where it is said to occur abundantly, but as it was 

 supposed to be a common mineral only a small specimen was 

 taken away, which he generously gave to the author for 

 determination and investigation. 



As anthophyllite is only known from a few localities and as 

 many varieties which have been referred to the species are, 

 according to the analyses, impure or more or less decomposed 

 (indicated by a high percentage of water), a full description of 

 the pure and well crystallized North Carolina mineral seems 

 desirable, especially as the crystals are transparent, rendering 

 it possible to make a fuller determination of the optical prop- 

 erties than has yet been made. The mineral occurs in pris- 

 matic crystals, sometimes several centimeters long and nearly 

 5 mm wide in the greatest diameter, imbedded in a green foliated 

 pennine, which latter shows in convergent polarized light 

 under the microscope a uniaxial interference figure with weak 

 positive double refraction. The only forms observed on the 

 anthophyllite are the prism 110, 1 and the brachy-pinacoid 

 010, i-i. No terminations could be found, the crystals when 

 traced to the very end in the pennine becoming irregular and 

 much broken. The prismatic faces have a fine luster but are 

 slightly etched ; examined under the microscope they appear to 

 be covered with delicate markings with irregular and mostly 



