304 PROCEEDINGS OF THE NATIONAL MUSEUM. vol. 58. 



crystal, with the lower portion incomplete where it has been attached 

 to a matrix of quartz crystals, several of which are embedded in the 

 lower portion. The color is smoky brown, similar to the color of 

 many smoky quartz crystals. The edges are exceptionally sharp 

 and the faces bright and lustrous, an exceptional feature for so large 

 a crystal. The upper figure on plate 18 shows the crystal reduced 

 one-fourth. 



Among a recent gift of Mr. C. S. Bement is a remarkably large and 

 clear crystal of danburite (U. S. Nat. Mus. 93384) from Obha, Japan. 

 The crystal is 3 centimeters long and 2 centimeters wide, colorless, 

 and transparent. The faces are sharp and brilliant. The prism 

 zone is striated, but the pyramids and domes have a very high polish. 



Another gift of Mr. Bement is a large specimen of the variety of 

 vesuvianite known as wiluite from the mouth of the Achtaragda 

 Kiver where it joins the Wilui River in eastern Siberia. The vesu- 

 vianite was first found here in 1790, but because of the remoteness 

 of the region specimens in collections are somewhat rare. The per- 

 fection of the crystals and the pleasing combination of dark green, 

 highly lustrous crystals, and light gray background make them much 

 sought after. The specimen presented by Mr. Bement (93387) 

 measures 18 by 18 centimeters and shows 15 large, brilliant, and well- 

 formed individuals on one face. The most prominent face is the 

 prism of the second order and they are terminated by the pyramid 

 and base. Through the matrix are scattered small crystals of ach- 

 taragdite, showing as triangular cross sections. Plate 19 shows the 

 specimens somewhat reduced. 



From the same locality as the vesuvianite and occurring in the same 

 tuffaceous rock is a specimen of achtaragdite from Mr. Bement. 

 This mineral is unique in that its form is the tris tetrahedron. The 

 only other mineral showing this form alone is helvite, and for this 

 reason achtaragdite is considered pseudomorphous after that mineral. 

 In spite of its uncertain character as a definite species the unusual 

 size and habit of its crystal makes it one of the most interesting of 

 minerals. The specimen recently acquu-ed is a mass of the tuffa- 

 ceous rock with tliree well-formed achtaragdites over 3 centimeters 

 in length and a number of smaller ones. They are light gray in color 

 and project prominently from the matrix. The upper figure on 

 plate 20 illustrates the specimen described and shows well the form 

 of the crystals. 



Crystals of zincite are of great rarity, and the museum was fortunate 

 in acquiring by gift from Mr. C. S. Bement a specimen showing sLx, 

 the largest bemg over 3 centimeters in length. They are well defined 

 though not brilliant. Coating some of the crystals and lining some 

 of the cavities is the new mineral gageite. The lower figure on plate 

 20 shows the habit of the crystals. 



