TITLE: Andradite WS488 Garnet DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: WS488

MINERAL_TYPE: Nesosilicate

MINERAL: Andradite (Garnet group)

FORMULA: Ca3(Fe+3)2(SiO4)3

FORMULA_HTML: Ca3Fe+32(SiO4)3

COLLECTION_LOCALITY: Franklin, New Jersey

ORIGINAL_DONOR: Wards Scientific

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

SAMPLE_DESCRIPTION:

Forms series with Grossular and with Schorlomite.

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

40 kV - 30 mA, 7.3-9.5 keV
File: andr488,out,*.mdi (smear mount on quartz plate)
References: Borg and Smith (1969), JCPDS #10-288, DHZ, v. 1a (1982), Huebner's reference patterns
Found: Garnet; five unindexed weak to very weak reflections.

Comment: Well crystallized, but not exceptional. Additional reflections at 7.1, 3.55, 2.84, 1.63 angstroms. Garnet ao=11.93+/-3 angstroms, indicating presence of andradite or uvarovite in solid solution. Based on brownish color, concluded that this garnet is andradite component in solid solution with Gr, Sp, Alm, or Py, most likely grossular.

J.S. Huebner, J. Pickrell, T. Schaefer, written communication 1994

END_XRD_ANALYSIS.

COMPOSITIONAL_ANALYSIS_TYPE: EM(WDS) # XRF, EM(WDS), ICP(Trace), WChem


COMPOSITION: SiO2 34.71 wt% SiO2
COMPOSITION: TiO2 0.09 wt% TiO2
COMPOSITION: Al2O3 4.76 wt% Al2O3
COMPOSITION: Cr2O3 0.00 wt% Cr2O3
COMPOSITION: V2O3 0.01 wt% V2O3
COMPOSITION: FeO 21.47 wt% FeO
COMPOSITION: NiO 0.01 wt% NiO
COMPOSITION: MnO 9.45 wt% MnO
COMPOSITION: MgO 0.02 wt% MgO
COMPOSITION: CaO 25.70 wt% CaO
COMPOSITION: Total 96.23 wt%
COMPOSITION: O=Cl,F,S wt% #correction for Cl, F, S
COMPOSITION: New Total 96.23 wt%

COMPOSITION_TRACE: None

COMPOSITION_DISCUSSION:

Analysis by Gregg Swayze using the USGS Denver microprobe, average of 6 samples.

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

Optical examination gives the following mineral mode:

96 vol% andradite
4 vol% opaques (biotite?) not magnetite

Bimodal grain size distribution:

population 1 av gr sz = 150um vol%= 75
population 2 av gr sz = 10um vol%= 25%

av gr sz of all populations = 130um

Conchoidally fractured andradite grains with opaque inclusions in the grains. 10um sized andradite grains coat 60% of the surfaces of the larger grains. Large grain surfaces either conchoidal fractures or flat parting surfaces. No fizz from HCl. G. Swayze

END_MICROSCOPIC_EXAMINATION.

SPECTROSCOPIC_DISCUSSION:

END_SPECTROSCOPIC_DISCUSSION.

SPECTRAL_PURITY: 1_2_3_4_

LIB_SPECTRA_HED: where Wave Range Av_Rs_Pwr Comment

LIB_SPECTRA: splib04a r 412 0.2-3.0µm 200 g.s.=130 µm

LIB_SPECTRA: splib05a r ____ 0.2-3.0µm 200 g.s.=

LIB_SPECTRA: splib06a r ____ 1.5-25µm 250 g.s.=