LCT pegmatites: The application of RAMAN spectroscopy Sophie - - PowerPoint PPT Presentation

▶
lct pegmatites
SMART_READER_LITE
LIVE PREVIEW

LCT pegmatites: The application of RAMAN spectroscopy Sophie - - PowerPoint PPT Presentation

Oct 24, 2023 312 likes •623 views

Rapid field identification of mineral phases in LCT pegmatites: The application of RAMAN spectroscopy Sophie Perring, 4/09/2019 Co-author: Dr Nigel Brand The Problem! LCT pegmatites Many minerals are anhydrous Not SWIR active

slide-1
SLIDE 1

Rapid field identification of mineral phases in LCT pegmatites: The application of RAMAN spectroscopy

Sophie Perring, 4/09/2019

Co-author: Dr Nigel Brand

slide-2
SLIDE 2

The Problem!

slide-3
SLIDE 3

LCT pegmatites

  • Many minerals are anhydrous – Not SWIR active
  • Lithium silicates are of economic value

‒ Not detectable by XRF

  • Raman can readily identify dominant and associated

pegmatite minerals:

  • Quartz, most feldspars, white micas, Li-bearing minerals,

pollucite, garnet, topaz, beryl, carbonates, apatite, etc.

  • Pioneer Resources Sinclair Mine:
  • 8 000 Drill hole samples
  • 2 000 Grade control samples
  • Small case studies
slide-4
SLIDE 4

What is Raman

Rayleigh scatter Raman scatter

400 500 600 700 800 900 1000 1100 1200 500 1000 1500 2000

  • Monochromatic light from a laser is directed onto a

sample

  • Most of the light scatters and remains the same

frequency (Rayleigh)

  • A small percentage of the light shifts frequency as a

result of chemical vibration of bonds in a mineral (Raman)

  • Raman measures this subtle frequency shift: Raman

Shift

  • The vibrations are unique to the substance →

‘Fingerprint’ spectrum

  • Can identify the material

Spodumene

707 cm-1

slide-5
SLIDE 5

How does it work?

  • Spectral database of reference material
  • Custom LCT-pegmatite library of over 300 spectra

covering 56 minerals and key mixtures

  • Non-destructive mineral identification
  • No sample prep
  • Mineral samples doesn’t have to be dry
  • Analysis times vary from 30 seconds to 5 minutes

Raman library spectral match confirms spodumene

707 cm-1

slide-6
SLIDE 6

The Problem!

slide-7
SLIDE 7 400 600 800 1000 1200 1400 1600 500 1000 1500 2000 2500 3000 400 600 800 1000 1200 1400 1600 500 1000 1500 2000 400 600 800 1000 1200 1400 1600 500 1000 1500 2000 400 600 800 1000 1200 1400 1600 500 1000 1500 2000 2500 400 600 800 1000 1200 1400 1600 500 1000 1500 2000 2500 400 600 800 1000 1200 1400 1600 500 1000 1500 2000 2500 400 600 800 1000 1200 1400 1600 500 1000 1500 2000 2500 400 600 800 1000 1200 1400 1600 500 1000 1500 2000 2500 400 600 800 1000 1200 1400 1600 500 1000 1500 2000 400 600 800 1000 1200 1400 1600 500 1000 1500 2000 2500

The Solution

slide-8
SLIDE 8 400 600 800 1000 1200 1400 1600 500 1000 1500 2000 2500 3000 400 600 800 1000 1200 1400 1600 500 1000 1500 2000 400 600 800 1000 1200 1400 1600 500 1000 1500 2000 400 600 800 1000 1200 1400 1600 500 1000 1500 2000 2500 400 600 800 1000 1200 1400 1600 500 1000 1500 2000 2500 400 600 800 1000 1200 1400 1600 500 1000 1500 2000 2500 400 600 800 1000 1200 1400 1600 500 1000 1500 2000 2500 400 600 800 1000 1200 1400 1600 500 1000 1500 2000 2500 400 600 800 1000 1200 1400 1600 500 1000 1500 2000 400 600 800 1000 1200 1400 1600 500 1000 1500 2000 2500

The Solution

Petalite Pollucite Albite, Quartz Eucryptite Beryl Albite Microcline Amblygonite Spodumene Quartz

slide-9
SLIDE 9

The Application

slide-10
SLIDE 10

The Application

slide-11
SLIDE 11

Pollucite

slide-12
SLIDE 12

Pollucite Petalite

slide-13
SLIDE 13

Pollucite Petalite Eucryptite

slide-14
SLIDE 14

Raman Applications

  • Applied to RC Chips, diamond core or hand

specimens

  • Identify the dominant mineralogy
  • Immediate verification or identification
  • Geologist logging
  • Grade control
  • Identifying mineral zones down a drill hole
  • Mapping mineral deposits
slide-15
SLIDE 15

Bruker BRAVO

  • Field portable
  • Class 1M laser product (safe for all conditions of

use)

  • Duo LASER™ (785 and 1064 nm)
  • Spectral range 300 – 3200 cm-1
  • SSE™ (Sequentially Shifted Excitation)

‒ Fluorescence elimination

Charoy, B., Noronha, F. and Lima, A., (2001) The Canadian Mineralogist, 39(3), pp.729-746.

slide-16
SLIDE 16

Feature Extraction

  • Specialised spectral feature analysis
  • Peak position, width and height can provide

further mineralogical insight

  • Improves upon the automated matching of bulk

spectra

  • Aids the delineation of related minerals

Mica discrimination Feldspar discrimination

Mica 1 Mica 2 Feldspar 1 Feldspar 2

Spectral Feature 1 Spectral Feature 1 Spectral Feature 2 Spectral Feature 2

slide-17
SLIDE 17

Quick Analysis

  • Mineral identification within minutes
  • Can differentiate between visually similar minerals

e.g. white silicates

  • Can apply mineral identification to current and

future occurrences when logging core

slide-18
SLIDE 18
slide-19
SLIDE 19

1078.42 986.38 935.98 781.80 778.41 689.77 685.69 630.90 600.02 518.34 385.87 314.63

400 600 800 1000 1200 1400 1600 1800 Wavenumber cm-1 500 1000 1500 2000 2500

Quick Analysis

  • Minerals that had previously not been observed or

described for the deposit were identified

  • Previously classed as a Ca-rich plagioclase
  • Identified as a separate calcium silicate mineral

(Prehnite) Sinclair Dome Sample Reference Prehnite Spectrum

Quartz Peak

slide-20
SLIDE 20

Log Drill Holes

  • Can identify the dominant mineral components
  • Identify mineral zones down hole
  • Can be applied to grade control in conjunction

with pXRF during ore extraction

slide-21
SLIDE 21
  • Provide data for mineral mapping
  • Gives comprehensive mineral overviews
  • Can be used to modify alteration maps in

preparation for further exploration

Mapping

slide-22
SLIDE 22

Potassium > 5% K2O

slide-23
SLIDE 23

K-feldspar (Raman)

slide-24
SLIDE 24

Potassium > 5% K2O & K-feldspar (Raman)

slide-25
SLIDE 25

Sodium (>5% Na2O)

slide-26
SLIDE 26

Plagioclase(Na) (Raman)

slide-27
SLIDE 27

Sodium (>5% Na2O); Plagioclase(Na) (Raman)

slide-28
SLIDE 28

Raman K-feldspar, Plagioclase(Na)

slide-29
SLIDE 29

Summary

  • Field portable
  • Non-destructive
  • No sample prep required
  • Rapid mineral verification
  • Rapid mineral identification
  • Mineral mapping
  • Discovery
slide-30
SLIDE 30

Pioneer Resources Limited - David Crook and the geological staff are thanked for their assistance and encouragement of this project.

For more information on Raman spectroscopy visit: georaman.com OR portaspecs.com

Acknowledgments

Portable Spectral Services personnel, in particular Evangeline Burton and Emma Brand are thanked for assisting in collecting the data set and Nick Jenson for developing the “proof of concept” on LCT pegmatites.