Name: Monticellite CaMgSiO4
Type: Mineral
Class: Silicate
Subclass: Nesosilicate
Particle Size: Coarse
Sample No.: monticell_1
Owner: JHU
Wavelength Range: TIR
Origin: Magnet Cove, Arkansas via the Smithsonian (NMNH 79051-1)
Collection Date: N/A
Description: The sample was composed of one large fragment and two smaller ones, all from the same crystal.  The large fragment was 1 cm in diameter and 2.5 cm long, with the other pieces half as large.  Total weight was 7.5 g.  The sample was tan in color, with abundant (10-20%) calcite. Petrographic examination showed minor (<1%) alteration to green antigorite and a few opaque grains. Particle size was 75-250 micrometers. (Isolated tetrahedra); (OlivineGroup) Original ASTER Spectral Library name was jhu.nicolet.mineral.silicate.nesosilicate.coarse.montic1.spectrum.txt
Mineral:  Monticellite CaMgSiO4

Sample No.: minticell.1

XRD Analysis:  After treatment with sodium acetate solution to 
remove calcite, XRD showed the sample to be pure monticellite.  An 
extremely weak calcite band in the infrared spectra shows that a 
very minor amount of calcite remains.

Chemistry:  Microprobe analysis indicated homogeneity within and 
between grains.  There is a small amount of substitution of Mg by Fe, 
resulting in departure from the ideal formula.  Average of ten 
analyses:

SiO2	37.26
Al2O3	0.01
FeO	5.14
MgO	21.69
CaO	34.94
K2O	0.02
Na2O	0.02
TiO2	0.03
Cr2O3	0.04
	_____
Total	99.15
