and Equivalent Volume of some Mineral Species. 213 
Hornblende represented by Sis Migs 6a, has an equivaleut of 
227-74, which with a density 2°93, gives a volume of 77-7 ; mul- 
tiplying by six, we have 466 as the volume of tremolite, with the 
formula sis1Os«(MgisCas)O2s. The density above given is 
probably too low, for anthophyllite sis 1054, (MgisFec)Ozs with 
a density of 3:16 gives a volume of 447-2. Acmite belongs to 
the hornblende type, and is represented by sis «Os +, (fe: sNas)Oz, 
which with a density of 3-4, corresponds to a volume of 441. 
For some important observations upon the association of angite 
and hornblende, and their intermixture with grains of chrysolite 
and chabazite, see Sandberger in Poggendorf’s Annalen, vol. 
Ixxxiii, p. 453.* 
We subjoin in a tabular form, the formulas, densities and 
equivalents of the above species. 
Species, Formula. Density, | Volume. 
\Glauber-salt, S4NasO16, He0O020 1-469 | 438: 
Borax, BsNasO2s, Hz0O40 1°730 | 441°6 
Spodumene, sisoOQco, (al2aLisNaz) Os0 3°180 | 457- 
Diopside, } sis2O0s2 (Ca1sMgis) O26 3-240 | 457° 
Hedenbergite, sis20s2 (Ca1zFei12Mg) O26 3°500 | 462° 
Hudsonite, (siss al1o) Oas, (Fe16Ca7Mn) O24 | 3-460 | 448: 
Carinthite, (sia1 alz7) Oas, (FevMgi2Cas) O24 | 3-127 | 4428 
Wollastonite, siaaO44, Caz2022 2-900 | 446°1 
Tremolite, sisaOs54,(MgisCac) O24 2:930  466- 
jAnthophyllite, sis4Os4, (MgisFec) O24 3160 447-2 
Acmite, ) | sissOs4, (fer1sNac) O24 3°400 | 441- 
* Cited in this Journal, [2] vol. xii, p. 389. : 
+ Prof. E. J. Chagisins it en pent aie idea that Al2Og replaces Si O a, has ex- 
tended the same view to other sesquioxyds, as Fe203, 02Mns ete, and thus re- 
fers Rammelsberg’s erednerite 2Mn203, 8(BaO, CuO) to the augite type 2SI Os, 
. Looking upon i iOs laces sphene and 
epidote to the same general formula. Two communications by him in U 
Mag. for 1852, vol. iii, pp. 141, and 270, contain many ingenious and important 
generalizations with regard to mineralogical classification. 
