Sample Description USGS Spectral Library Version 7

USGS Spectral Library Version 7 Sample Description

Kokaly, R.F., Clark, R.N., Swayze, G.A., Livo, K.E., Hoefen, T.M., Pearson, N.C., Wise, R.A., Benzel, W.M., Lowers, H.A., Driscoll, R.L., and Klein, A.J., 2017, USGS Spectral Library Version 7: U.S. Geological Survey Data Series 1035, 61 p., https://doi.org/10.3133/ds1035
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TITLE: Lepidolite NMNH105538 DESCRIPT

DOCUMENTATION_FORMAT: MINERAL

SAMPLE_ID: NMNH105538

MINERAL_TYPE: Phyllosilicate

MINERAL: Lepidolite (Mica group)

FORMULA: K(Li,Al)3(Si,Al)4O10(F,OH)2

FORMULA_HTML: K(Li,Al)₃(Si,Al)₄O₁₀(F,OH)₂

COLLECTION_LOCALITY: Stewart Mine, San Diego County, California

ORIGINAL_DONOR: National Museum of Natural History

CURRENT_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

ULTIMATE_SAMPLE_LOCATION: USGS Denver Spectroscopy Laboratory

SAMPLE_DESCRIPTION:

Pink, lilac and gray mica.

IMAGE_OF_SAMPLE:

END_SAMPLE_DESCRIPTION.

XRD_ANALYSIS:

40 kV - 30 mA, 6.5-9.5 keV
File: lp105538.mdi (random mt)
References: JSH's reference patterns; JCPDS patterns for micas; Deer, Howie, & Zussman (1962); Bailey (1984a,b); PDF2 #24-062, 24-0594, 06-0263, 43-0685, 42-1399, 42-0604, 15-0062
Found: Two polytypes of lepidolite-group micas

Comment: Peaks are narrow and symmetric; some peak tips are split as if two similar phases (or compositions of one phase) are present. The alpha1-alpha2 components are not resolved. Huebner's reference patterns and JCPDS patterns for lepidolite, muscovite 2M1 and 2M2, and Zinnwaldite 1M are similar to that obtained from the sample. No single mineral pattern successfully accounts for all of the peaks observed in the pattern. Search matches based upon the eight strong reflections and upon the full profile did not account for the intensity of the reflection at 4.96 Angstroms or yield otherwise convincing results. Best agreement was obtained with PDF2 #15-0062, lepidolite 12O, which has a strong (00.24) superlattice reflection at 4.96 Angstroms. but which, surprisingly, was not identified by the search-match routines. Minor reflections are adequately explained the addition of 43-0692, lepidolite 2M2. The original sample is formed of compact masses of lavender crystals characteristic of lepidolite.

END_XRD_ANALYSIS.

COMPOSITIONAL_ANALYSIS_TYPE: None # XRF, EPMA, ICP(Trace), WChem
COMPOSITION_TRACE:

None

COMPOSITION_DISCUSSION:

None

END_COMPOSITION_DISCUSSION.

MICROSCOPIC_EXAMINATION:

END_MICROSCOPIC_EXAMINATION.

SPECTROSCOPIC_DISCUSSION:

END_SPECTROSCOPIC_DISCUSSION.

SPECTRAL_PURITY: 1b2c3c4_ # NMNH105538 # 1= 0.2-3, 2= 1.5-6, 3= 6-25, 4= 20-150 microns