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(For further information on spectrsocopy, see:
http://speclab.cr.usgs.gov)
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 un indexed 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 KEYWORD |
Oxide ASCII |
Amount | Weight Percent, % |
Oxide html |
|---|---|---|---|---|
| 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% | a|
| COMPOSITION: | O=Cl,F,S | wt% | #correction for Cl, F, S | |
| COMPOSITION: | New Total | 96.23 | wt% | a
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 avg. grain size = 150um vol%= 75
population 2 avg. grain size = 10um vol%= 25%
avg. grain size 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: 1c2_3_4_ # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
| 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 1037 | 0.2-3.0µm | 200 | g.s.= |
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