Automated Mineralogy

A machine learning solution to geological sample characterisation
Automated Mineralogy

Introduction

Automated Mineralogy is 'a range of analytical solutions that are used to quantitatively evaluate the mineralogy of samples'. 
Essentially, automated mineralogy is a software that can be used in conjunction with SEMs (Scanning Electron Microscopy) and associated detectors (EDS and BSE (Backscattered Electron)) that takes multiple different outputs provided by the microscope of a heterogeneous sample, which can then be used to categorise sections of the sample to produce a full characterisation of the sample in respect to: 
  • bulk mineralogy
  • mineral association
  • liberation data
  • free surface area
  • porosity
  • element concentration
  • grain size.
    
   
   
    

The software has mainly been utilised within the geosciences, hence the use of geoscientific language such as minerals, although, it can have its uses outside of the geosciences such as: forensic sciences, archaeology and material sciences. Essentially any homogenous sample could be analysed using automated mineralogy if any of the applications could supply useful data. 

<p>Samples for automated mineralogy&nbsp;</p>

Types of samples that can be used for Automated Mineralogy

How it works

The software works by using a multitude of outputs from SEM, most notably using EDS data and BSE images, which are used in conjunction to separate out phases, minerals or grains, depending on the sample. This is then used to characterise sample using a classification scheme that can be one that has already been created, or a unique user input one if the sample has a specific characterisation scheme needed.

Different Automated mineralogy software characterise samples in different methods. We have two types of software in house. Zeiss’s Mineralogic (available spring/summer 2022) and Oxford Instrument’s AZtec Mineral.

The different software work better for different samples depending on what kind of analysis is needed.

<p>BPS of gold sample</p>

Zeiss’s Mineralogic uses pixel by pixel analysis and characterises samples via their chemical composition. Each pixel is assigned a mineral/element depending on its chemical composition which is compared to the characterisation scheme. Greyscale on BSE tends to get used for specific mineral searches, if looking for grains of a specific greyscale, and then is characterised via chemical methods.  
Works for: 
  • whole samples 
  • crushed/grain samples 
  • specific mineral searches 
  • elemental assays.

Oxford Instruments' software firstly separates our different grains and crystals by analysing the BSE image of the sample, splitting images into distinctive features depending on their greyscale. Each feature is then analysed by EDS to gain an average composition of the feature, which is then assigned a mineral/element from the characterisation scheme. 
Works for: 
  • whole samples 
  • crushed/grain samples 
  • porosity  
  • grain size analysis.

<p>AZtec Mineral</p>
Capabilities
  • Bulk mineral analysis
  • Particle mineral analysis
  • Specific mineral search 
  • Trace mineral search 
  • Porosity measurements
  • Grain size analysis
  • Elemental assay
  • Liberation analysis
Software available in PEMC
 
  • Oxford Instruments – AZtec Mineral on our JEOL 7001 FE SEM
  • Zeiss- Mineralogic on our Zeiss Sigma 300 FEG SEM – available Summer 2022