Sni ALLBR.] 



Spodti hi en c from 8a n Diego Coun ty . 



273 



one crystal, the etch figures penetrate the crystal, emerging on 

 the opposite clinopinacoid. These cavities are usually partially 

 choked up by a limonitic earthy substance. 



Etch figures also cover the rounded ends of the crystals, but 

 their relation to the structure of the crystal cannot be determined 

 owing to the lack of definite terminal faces. 



PHYSICAL PROPERTIES. 



General Properties. — In its physical properties, with the 

 exception of the color the mineral does not vary from normal 

 spodumene. The color although rare is not new as it has been 

 noted on some of the spodumene from Brauchville, Conn., des- 

 cribed by Brush and Dana.* To quote a few words from their 

 paper (p. 258) — "The unaltered spodumene, of a fine amethyst- 

 ine color, ... In the better specimens the spodumene is 

 perfectly transparent, sometimes colorless, and again of a beau- 

 tiful rose-pink or amethystine-purple color." This description 

 fits admirably with the San Diego spodumene. One specimen is 

 colorless while the others are of a rose- pink, magenta or 

 amethystine-purple col< >r . 



The cleavage parallel to the unit prism is highly perfect. 

 No parting parallel to the orthopinacoid was noticed on any of 

 the crystals. All of the crystals are transparent aud show no 

 trace of alteration, being remarkably fresh and thus differing 

 materially from the New England spodumene. The hardness of 

 the mineral lies between that of quartz and beryl. An inter- 

 esting observation may be mentioned here. On cutting a crystal 

 with a carborundum saw, the mineral became strongly luminous. 



The clearest transparent piece was taken for analysis and the 

 specific gravity of it taken by suspension in water. The piece 

 weighed about 10 grams. The specific gravity was determined 

 as 3.189. This agrees very well with the result obtained on the 

 pink Brauchville, Conu. spodumene by Brush and Dana, namely, 

 3.193. 



The mineral fuses easily to a clear glass coloring the flame an 

 intense red. 



Optical Properties. — The pleochroism is a very striking pro- 

 perty of the mineral. The colors are 3 = magenta or amethyst- 



* Loc. oit. 



