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DOCUMENTATION_FORMAT: MINERAL
SAMPLE_ID: HS21.1B, HS21.2B, HS21.3B, HS21.4B
MINERAL_TYPE: Phyllosilicate
MINERAL: Talc
FORMULA: Mg3Si4O10(OH)2
FORMULA_HTML: Mg3Si4O10(OH)2
COLLECTION_LOCALITY: Swain County, North Carolina
ORIGINAL_DONOR: Hunt and Salisbury Collection
CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory
ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory
SAMPLE_DESCRIPTION:
"S-20. Talc. Swain Co., N.C. (21B). Talc is a hydrous magnesium silicate, essentially Mg3Si4O10(OH)2, of secondary origin. It may be found in altered igneous rocks, but is more typical of metamorphic varieties. It is formed by alteration of magnesian silicates such as olivine, pyroxenes and amphiboles. Talc may bear a little iron, aluminum or nickel, and ferrous ion in this talc probably accounts for the iron bands on either side of 1µ. The sample appears uncontaminated by unaltered pyroxene, which might otherwise contribute these bands. Hydroxyl bands are particularly strong and sharp in this sample, which displays them near 1.4µ and 2 to 2.6 µ. The extremely sharp, but weak feature at 0.95µ must also be due to OH."
Hunt, G.R., J.W. Salisbury, 1970, Visible and near-infrared spectra of minerals and rocks: I. Silicate minerals. Modern Geology, v. 1, p. 283-300.
Grain size fractions are indicated by the extension after the sample number:
.1B = <5 µm
.2B = <74 µm
.3B = 74-250 µm
.4B = 250-1200 µm
IMAGE_OF_SAMPLE:
END_SAMPLE_DESCRIPTION.
XRD_ANALYSIS:
Talc + med. amount chlorite; M: ~2% chlorite, less than 2% magnetite (Norma Vergo)
END_XRD_ANALYSIS.
COMPOSITIONAL_ANALYSIS_TYPE: EM (WSA) # XRF, EPMA, ICP(Trace), WChem
| COMPOSITION KEYWORD |
Oxide ASCII |
Amount | Weight Percent, % |
Oxide html |
|---|---|---|---|---|
| COMPOSITION: | SiO2 | 60.47 | wt% | SiO2 |
| COMPOSITION: | TiO2 | 0.04 | wt% | TiO2 |
| COMPOSITION: | Al2O3 | 0.12 | wt% | Al2O3 |
| COMPOSITION: | Fe2O3 | 0.87 | wt% | Fe2O3 |
| COMPOSITION: | FeO | 0.10 | wt% | FeO |
| COMPOSITION: | MnO | 0.01 | wt% | MnO |
| COMPOSITION: | MgO | 30.29 | wt% | MgO |
| COMPOSITION: | ZnO | 0.00 | wt% | ZnO |
| COMPOSITION: | BaO | 0.01 | wt% | BaO |
| COMPOSITION: | CaO | 0.05 | wt% | CaO |
| COMPOSITION: | Na2O | 0.04 | wt% | Na2O |
| COMPOSITION: | K2O | 0.00 | wt% | K2O |
| COMPOSITION: | P2O5 | 0.27 | wt% | P2O5 |
| COMPOSITION: | Cl | 0.01 | wt% | Cl |
| COMPOSITION: | F | 0.51 | wt% | F |
| COMPOSITION: | LOI | 5.31 | wt% | LOI |
| COMPOSITION: | Total | 92.31 | wt% |
COMPOSITION_TRACE: None
COMPOSITION_DISCUSSION:
Because of variability in the analyses, most Fe is probably Fe+2.
Average of 6 point analysis.
NOTE: Conversion of Fe2O3 to FeO. This sample has too much
chlorite. Therefore, Fe ratios are unusable.
END_COMPOSITION_DISCUSSION.
MICROSCOPIC_EXAMINATION:
END_MICROSCOPIC_EXAMINATION.
SPECTROSCOPIC_DISCUSSION:
END_SPECTROSCOPIC_DISCUSSION.
SPECTRAL_PURITY: 1b2_3_4_ # HS21.1B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
SPECTRAL_PURITY: 1b2_3_4_ # HS21.2B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
SPECTRAL_PURITY: 1b2b3b4b # HS21.3B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns
SPECTRAL_PURITY: 1b2_3_4_ # HS21.4B # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns