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DOCUMENTATION_FORMAT: MINERAL
SAMPLE_ID: NMNH94217-1.a, NMNH94217-1.b, NMNH94217-1.c
MINERAL_TYPE: Cyclosilicate
MINERAL: Elbaite (Tourmaline group)
FORMULA: Na(Li,Al)3Al6(BO3)3Si6O18(OH)4
FORMULA_HTML: Na(Li,Al)3Al6(BO3)3Si6O18(OH)4
COLLECTION_LOCALITY: Sao Jose De Brejuada, Minas Gerais, Brazil
ORIGINAL_DONOR: National Museum of Natural History (Smithsonian)
CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory
ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory
SAMPLE_DESCRIPTION:
Forms series with Dravite.
"Results of petrographic examination: A purple sudhedral crystal, transparent with some green coloration to one end. Sample is ~5mm x 2cm x 2cm. Under petrographic microscope, sample appears pure, clear."
Salisbury, J. W., Walter, L. W., and Vergo, N., 1987, Mid-Infrared (2.1-25µm) Spectra of Minerals: First Edition, U.S. Geological Survey Open File Report 87-263.
Sample is in the following sieve intervals: (a) 250µm, (b) 150µm, (c) less than 74µm
IMAGE_OF_SAMPLE:
END_SAMPLE_DESCRIPTION.
XRD_ANALYSIS:
Elbaite plus many peaks (Norma Vergo).
END_XRD_ANALYSIS.
COMPOSITIONAL_ANALYSIS_TYPE: EPMA # XRF, EPMA, ICP(Trace), WChem
| COMPOSITION KEYWORD |
Oxide ASCII |
Amount | Weight Percent, % |
Oxide html |
|---|---|---|---|---|
| COMPOSITION: | SiO2 | 36.83 | wt% | SiO2 |
| COMPOSITION: | TiO2 | 0.04 | wt% | TiO2 |
| COMPOSITION: | Al2O3 | 40.56 | wt% | Al2O3 |
| COMPOSITION: | FeO | 0.12 | wt% | FeO |
| COMPOSITION: | MnO | 4.40 | wt% | MnO |
| COMPOSITION: | MgO | 0.03 | wt% | MgO |
| COMPOSITION: | CaO | 0.13 | wt% | CaO |
| COMPOSITION: | Na2O | 2.37 | wt% | Na2O |
| COMPOSITION: | K2O | 0.01 | wt% | K2O |
| COMPOSITION: | Total | 84.49 | wt% | |
| COMPOSITION: | O=Cl,F,S | wt% | #correction for Cl, F, S | |
| COMPOSITION: | New Total | wt% |
COMPOSITION_TRACE: None
COMPOSITION_DISCUSSION:
Microprobe analysis showed the sample to be homogeneous within and between grains. Average of seven analyses does not include lithium, boron or water, but demonstrates the presence of sufficient manganese to indicate that this is not end member elbaite.
Salisbury, J. W., Walter, L. W., and Vergo, N., 1987, Mid-Infrared (2.1-25µm) Spectra of Minerals: First Edition, U.S. Geological Survey Open File Report 87-263.
END_COMPOSITION_DISCUSSION.
MICROSCOPIC_EXAMINATION:
Grain Size distributions:
250 µm fraction: bimodal gr sz dist.
population 1 avg. grain size size = 662 µm 99 vol%
population 2 avg. grain size size = 10 µm 1 vol%
avg. grain size entire population = 659 µm
74 < x < 250 µm fraction: avg. grain size = 196 µm
< 74 µm fraction: bimodal gr sz dist.
population 1 avg. grain size = 68 µm 75 vol%
population 2 avg. grain size = 15 µm 25 vol%
avg. grain size entire population = 59 µm
Samples are very pure. No cleavage, uniaxial (+), slight pink color. All consistent with tourmaline. M. Cowoski and G. Swayze.
END_MICROSCOPIC_EXAMINATION.
SPECTROSCOPIC_DISCUSSION:
END_SPECTROSCOPIC_DISCUSSION.
SPECTRAL_PURITY: 1b2b3b4b # Elbaite NMNH94217-1.a # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
SPECTRAL_PURITY: 1b2b3b4b # Elbaite NMNH94217-1.b # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
SPECTRAL_PURITY: 1b2_3_4_ # Elbaite NMNH94217-1.c # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns