1 882.] Mineralogy. 337 



divison, System for the next, Series for the third, Stage for the 

 fourth, for the fifth Assize or Couche. Formation was not 

 adopted because it has other meanings. M. St. Meunier has suc- 

 ceeded in artificially forming enstatite.a mineral which is common 

 in meteorites, and in a section shows fan-shaped or star-shaped forms. 

 It is out of those forms, producible (as M. St. Meunier remarks) 

 in a porcelain tube heated to redness, that the fancy of Mr. Otto 

 Hahn constructed the crinoids and sponges which form the sub- 

 ject of his work. At a recent meeting of the New York 



Acad, of Sciences, Dr. Alexis A. Julien read an able paper upon 

 the volcanic tuffs of Idaho and other western localities. 



MINERALOGY. 1 

 Helvite from Amelia county, Virginia. — Among some min- 

 erals recently obtained from the mica mine near Amelia Court- 

 house, Virginia, already famous for its microlite, was a yellow, 

 crystalline substance which upon examination has proved to be 

 Helvite. The mineral occurs in crystals and friable crystalline 

 masses imbedded in bluish-white orthoclase, and is generally 

 associated with pale red topazolite. While no crystals were 

 found sufficiently perfect to allow of measurement, the absence 

 of any action upon polarized light proved their isometric char- 



The mineral has a hardness of about 6, a specific gravity of 

 4.306 (Haines), a sulphur-yellow color, a somewhat resinous lus- 

 tre, and is partially translucent. It fuses at about 4 with intu- 

 mescence to a brown glass, gives no water in the closed tube, 

 and with the fluxes gives the reactions for manganese. Fused on 

 charcoal with soda, it gives a hepar. It is soluble in hydrochloric 

 acid, evolving sulphuretted hydrogen and leaving a residue of 

 gelatinous silica. 



My friend, Mr. Reuben Haines, has been kind enough to con- 

 tribute the following analysis : 



Gangue (SiO a insoluble in NaC0 3 ) 9-22 



The mineral was dissolved in HCI, and the " gangue " found by 

 repeatedly washing the total SiO* on the filter with a hot concen- 

 trated solution of NaCO,, which removed all the soluble Si0 2 . By . 



