256 DESCRIPTIONS OF MINERALS. 
disseminated in basaltic rocks, which never so occurs; and 
in its cleavage. From obsidian or yolcanic glass it differs 
in its infusibility. 
Obs. Occurs as a rock formation; also disseminated 
through basalt and other eruptive rocks, and is a charac- 
teristic mineral of some varieties of them. Has been 
found in New Hlampshire, Canada, and elsewhere. Asa 
rock it occurs in North Carolina, and Pennsylvania. It 
also occurs 11 Many meteorites. Boltonite, from limestone 
at Bolton, Mass., is a variety of chrysolite. 
Sometimes used as a gem, but it is too soft to be valued, 
and is not delicate in its shade of color 
Torsterite is a magnesian chrysolite Mg:0,Si; Mayalite, an iron 
chrysolite, Fe,O,Si ; Monticellitc, a calcium-magnesium, Ca Mg» O, Si ; 
Hortonolite, an iron- -magnesium chrysolite from Orange County, Neyer 
Repperite, an iron-manganese-zine chrysolite from Stirling Hill, ING she 
Tephroite, a manganese chrysolite Mn, O, $i, from Stirling Hill, Ned. 
Knebelite, a manganese- iron chrysolite, MnFe O, Si, from Dannentoel 
Sweden. 
Leucophanite and meliphanite are species containing the element 
glucinum (beryllium), the former greenish yellow and G=2'97, the 
latter yellow and G=3'018. From Norway. 
Wohleritz contains zirconium, and also columbium ; color light yel- 
low. G=8-41. 
Willemit2 is a zine unisilicate, Zn,O,Si. See page 157. 
DMoptase is a copper silicate, which, making the watcr basic, is a 
unisilicate, H,CuO,8i. See page 141. 
Friedelite is a yose-red manganese silicate of the gencral formula 
R, O, Si,in which R consists of manganese and hydrogen in the atomic 
ratio 2:1. 
JTelwite (Helvin). Isometric ; in tetrahedral crystals. Color honey- 
yellow, brownish, greenish. Lustre vitreo-resinous. H.=6-6°0. 
G.=3'1.32. Contains manganese, iron, and glucinnm, and some 
sulphur. From Saxony, and Norway. 
Danaiite. Isometric ; in octahedral crystals. Color flesh-red to 
gray. Lustre vitreo-resinous. H.=55. G.=3'427. Contains zinc, 
glucinum, iron, manganese. Found disseminated through the granite 
at Rockport, Cape Ann, Mass , and also near Gloucester, Mass. 
EHulytite is a bismuth silicate, and Bismutoferrite a bismuth-and- 
iron silicate, 
Garnet. 
Isometric. Common in dodecahedrons (fig. 1), also in 
trapezohedrons (fig. 2), and both forms are sometimes vari- 
ously modified. Cleavage parallel to the faces of the dode- 
cahedron ; sometimes rather distinct. Also found massive 
granular, and coarse lamellar. 

