Mineral Resources Program

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Selected mineral specimen images and videos about Program activities.

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June 4, 2019

CRITICAL MINERALS in RENEWABLE ENERGY

To make America’s economy and defense more secure, the Administration has released “A Federal Strategy to Ensure Secure and Reliable Supplies of Critical Minerals.” Among other roles, these minerals are vital to renewable energy infrastructure like solar panels, wind turbines, and batteries.

Solar Panels  |  Wind

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Summary of OH-related near-infrared spectral features of unexpanded and expanded vermiculite ores.
February 13, 2019

Summary of OH-related near-infrared spectral features.

Table 6.  Summary of OH-related near-infrared spectral features of unexpanded and expanded vermiculite ores.

Notes: Vibrational positions from spectra of handpicked, ground mica flakes from the unexpanded GDS469 ore sample from Libby, MT; and the expanded vermiculite ores as noted.  Vibrational assignments from this study.  oa = OH overtone;

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Accuracy of expanded vermiculite ore spectral source determinations.
February 13, 2019

Accuracy of expanded vermiculite ore spectral source determinations.

Table 7.  Accuracy of expanded vermiculite ore spectral source determinations and impurity detections. 

Notes: Samples evaluated for impurities using the Modified Cincinnati Method (MCM) with separates examined by Scanning Electron Microscope – Energy-Dispersive X-Ray Spectroscopy (SEM-EDS) for the presence of amphibole, talc, and/or serpentine, and using the

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ANOVA with post hoc multiple pairwise statistical comparison between compositions of unexpanded vermiculite ore samples examined
February 13, 2019

ANOVA with post hoc multiple pairwise statistical comparison

Table A1.  ANOVA with post hoc multiple pairwise statistical comparison between compositions of unexpanded vermiculite ore samples examined in this study.

 

Notes: Mg fraction = Mg/(Mg+Aloct +Feoct), tetrahedral Al fraction = (Altet + Si), total Al, and total Fe are based on Electron Probe MicroAnalysis (EPMA) of the

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ANOVA with post hoc multiple pairwise statistical comparison between compositions of expanded vermiculite ore samples examined.
February 13, 2019

ANOVA with post hoc multiple pairwise statistical comparison.

Table A2.  ANOVA with post hoc multiple pairwise statistical comparison between compositions of expanded vermiculite ore samples examined in this study. 

Notes: Mg fraction = Mg/(Mg+Aloct +Feoct), tetrahedral Al fraction = (Altet + Si), total Al, and total Fe are based on Electron Probe MicroAnalysis (EPMA) of the expanded ore

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ANOVA with post hoc multiple pairwise statistical comparison between compositions of selected unexpanded vermiculite ore.
February 13, 2019

ANOVA with post hoc multiple pairwise statistical comparison.

Table A3.  ANOVA with post hoc multiple pairwise statistical comparison between compositions of the selected unexpanded vermiculite ore samples and all other unexpanded vermiculite ore samples from the four major historical sources examined in this study.

Notes: Mg fraction = Mg/(Mg+Aloct +Feoct), tetrahedral Al fraction = (Altet +

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ANOVA with post hoc multiple pairwise statistical comparison between compositions of selected unexpanded vermiculite ore samples
February 13, 2019

ANOVA with post hoc multiple pairwise statistical comparison.

Table A4.  ANOVA with post hoc multiple pairwise statistical comparison between compositions of selected unexpanded vermiculite ore samples examined in this study. 

Notes: Mg fraction = Mg/(Mg+Aloct +Feoct), tetrahedral Al fraction = (Altet + Si),  total Al, and total Fe are based on Electron Probe MicroAnalysis (EPMA) of the

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Electron probe microanalysis analyses and resulting formula of an unexpanded VTx-1 Mg-vermiculite sample from Llano, Texas.
February 13, 2019

Electron probe microanalysis analyses and resulting formula.

Table A5.  Electron probe microanalysis analyses and resulting formula of an unexpanded VTx-1 Mg-vermiculite sample from Llano, Texas. 

Notes:

a Microprobe data for all Fe are binned into FeO.

b There are no data on H2O content. 

 Expanded vermiculite ores examined in this study: their sources and amphibole, talc, and/or serpentine impurities.
February 13, 2019

Expanded vermiculite ores examined in this study

Table 1.  Expanded vermiculite ores examined in this study: their sources and amphibole, talc, and/or serpentine impurities.

Notes: XRD = X-ray diffraction analysis of bulk ore samples (B) and sink fractions (S).  SEM-EDS = Scanning Electron Microscope – Energy-Dispersive X-Ray Spectroscopy.  Band Depth Ratio = 1.40/1.42-µm band depth ratio.  The use of "sodic-

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Average EPMA chemical analyses and calculated mineral formulas of selected unexpanded vermiculite ores.
February 13, 2019

Average EPMA chemical analyses and calculated mineral formulas.

Table 2.   Average EPMA chemical analyses and calculated mineral formulas of selected unexpanded vermiculite ores.

Notes: Compositions of bulk samples not individual minerals.  n = number of microprobe spot analyses collected on multiple mica flakes used to calculate the averaged composition of each sample.   ---- = not enough cation Al and/or Mg to assign to this

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Mössbauer spectral parameters obtained at 295 K for selected unexpanded vermiculite ore samples.
February 13, 2019

Mössbauer spectral parameters for vermiculite ore.

Table 3.  Mössbauer spectral parameters obtained at 295 K for selected unexpanded vermiculite ore samples.

Notes: IS = isomer shift; QS = quadrupole splitting; Width = absorption peak width; Area = % area of an absorption peak relative to other peaks in the spectrum.  

a Oh1 & Oh2 = 1st and 2nd octahedral Fe3+

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Summary of OH-related mid-infrared (MIR) spectral features of unexpanded and expanded vermiculite ores.
February 13, 2019

Summary of OH-related mid-infrared (MIR) spectral features.

Table 5.  Summary of OH-related mid-infrared (MIR) spectral features of unexpanded and expanded vermiculite ores.

Notes: Vibrational positions from spectra of handpicked, ground mica flakes from the unexpanded GDS469 ore sample from Libby, MT; the unexpanded ALB5SA00 ore sample from Palabora, S. Africa; and the expanded vermiculite ores as noted.  Vibrational

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