Petrography and Microanalysis

The BGS has modern, comprehensive and well-equipped petrological and microscopical laboratories covering a wide-range of analytical techniques. These are staffed by expert mineralogists, petrologists and geochemists with very significant experience in academic and commissioned research and the provision of analytical services to industrial and government clients.

Equipment and techniques
  • Optical petrography and ore microscopy
    The BGS laboratories are well equipped with high-quality research-standard petrological microscopes for transmitted and reflected light, with the capability for digital microphotography. The optical microscope facility includes a modern Zeiss Axioplan 2 polarising microscope with high-resolution digital camera facility. In addition, a number of other Zeiss petrological microscopes are available providing for multiple user access. In addition, facilities are available for binocular stereomicroscopy, including a modern Olympus SZX-10 Stereophotomicroscope equipped with a high-resolution Peltier-cooled digital camera, as well as a number of other binocular microscopes available. The digital photomicroscopes are equipped with PC workstations and software for basic processing and labelling of images.


    • Optical petrographic image (crossed polars) of peridotite

    Optical petrographic image (crossed polars) of peridotite.

    reflected light petrographic image showing native copper enclosed beneath layers of red cuprite

    Reflected light petrographic image showing native copper enclosed beneath layers of red cuprite.


    Modal analysis (point counter) and facilities for petrographical image analysis are available for quantitative analysis of mineralogy and fabric.

    Access to vitrinite reflectance/coal petrology is also available.

  • Scanning electron microscopy - the BGS has two scanning electron microscopes:
  • A LEO (Zeiss) 435VP Variable Pressure Digital Scanning Electron Microscope (SEM), equipped with capability for, secondary electron (SEI) and backscattered-electron (BSEM) imaging, cathodoluminescence (SEMCL) imaging (Oxford Instruments (Gatan) MiniCL detector) and transmission scanning electron microscopy. The instrument is also equipped with modern Oxford Instruments INCA energy-dispersive analysis (EDXA) system with thin-window SiLi X-ray detector capable of detecting elements in ranging in Periodic Table from B to U. Both qualitative and quantitative microanalysis can be undertaken simultaneously during SEM observation, and the equipment can also produce X-ray element distribution maps using the INCA EDXA system. The SEM instrument is also equipped with an Oxford Instruments (Gatan) CT1500 cryogenic cold-stage and sample transfer system, and a purpose-built cryogenic sample preparation system. This enable specialised SEM-EDXA analysis of beam-sensitive or volatile materials as frozen/moist samples and allows SEMCL imaging at low temperatures (down to -180°C) which can reveal fabrics and features not visible under normal SEM operating conditions. The As well as being able to operate as a conventional high-vacuum SEM, the LEO 435VP SEM also has the specialised capability of being able operate under variable pressure (low vacuum) conditions, enabling imaging of uncoated SEM samples, moist samples, or problematic samples (i.e. difficult to coat) prone to sample charging (e.g. friable samples, fibrous or dusty materials). An Oxford Instruments (Gatan) MonoCL cathodoluminescence spectrometer system is also available for very specialised, full-spectral SEMCL analysis applications.


    • Backscattered scanning electron image of oolitic sandstone cemented by anhydrite

    Backscattered scanning electron image of oolitic sandstone cemented by anhydrite.

    SEM image of fibrous calcite binding soil particles

    SEM image of fibrous calcite binding soil particles.


  • A Leica (Zeiss) Stereoscan S360 scanning electron microscope with capability for, secondary electron (SEI) and backscattered-electron (BSEM) imaging, cathodoluminescence (SEMCL) imaging (Oxford Instruments MiniCL detector). This is also equipped with modern Oxford Instruments INCA energy-dispersive analysis (EDXA) system with thin-window GeLi X-ray detector capable of detecting elements in ranging in Periodic Table from B to U. The instrument is a conventional high-vacuum SEM instrument suitable for routine high-resolution SEM applications.
  • The SEM Laboratory is supported by a well-equipped sample preparation facility, with sample preparation equipment to enable: freeze drying and critical-point drying of wet materials; vacuum evaporation coating for routine carbon and gold coating, or more specialised mixed coating; argon sputter-coating for gold.
  • The facility handles a wide range of geological and environmental sample types and forms, including: rocks, soils, unconsolidated sediments, cement and concrete, metals, experimental reaction products and precipitates, dust and filter materials, colloid samples, ices and gas hydrates, biological and microbiological materials and biofilms, and radioactively-contaminated materials.


  • Electron probe micro-analysis
    • A Cameca SX50 electron probe microanalyser (EPMA) instrument is available. This is equipped with three computerised wavelength dispersive X-ray spectrometers and a PGT energy dispersive X-ray microanalysis system. The equipment is routinely used for: quantitative major and trace element microchemical analysis of minerals and solid phase, automated searching for rare-phases (e.g. gold, platinum, heavy metals) in polished petrographical sections, microchemical mapping, metallogenesis research, heavy mineral analysis, and petrogenesis.
  • Routine quantitative major element microchemical analysis of minerals can also be undertaken by EDXA using either the LEO 435VP or Leica S350 SEM instruments.


    • X-ray-elemental map showing the distribution of copper (Cu) in a polished thin section of Permian mudstone containing altered native copper sheets

    X-ray-elemental map showing the distribution of copper (Cu) in a polished thin section of Permian mudstone containing altered native copper sheets .



  • Cathodoluminescence microscopy
    The facility operates a Technosyn 8200 MkII cold cathode luminoscope attached to an optical microscope for optical cathodoluminescence microscopy applications. The technique is particularly useful for petrographical analysis of carbonate mineral and rock fabrics, SEM-based cathodoluminescence, including both basic imaging and specialised spectral analysis (visible and IR range) is available on the scanning electron microscopes (see Scanning electron microscopy above).


    • Optical cold cathododoluminescence image showing complex fabric in calcite cements

    Optical cold cathododoluminescence image showing complex fabric in calcite cements.

    Optical cold cathodoluminescence image of zoning in calcite

    Optical cold cathodoluminescence image of zoning in calcite.


  • UV epifluorescence microscopy and fluorescence imaging
  • A Zeiss Universal polarising petrographical microscope equipped with UV epifluorescence attachment for UV fluorescence microscopy. This is used in applications to geomicrobiological studies, and for the observation of fluorescence in organic fluid inclusions and other organic materials.
  • Facility for laser fluorescence imaging using an Amersham Biosciences STORM 860 digital laser-stimulated fluorescence scanner, with the capability for red (635 nm) and blue (450 nm) fluorescence excitation imaging (see also Autoradiography)
  • Petrographical image analysis Computerised petrographical image analysis (PIA) is available using modern PIA software packages (e.g. AnalySIS [Olympus UK limited]). Digital petrographical images recorded from macrophotography, optical microscopy and scanning electron microscopy can be processed to provide a wide variety of quantitative information on mineral fabric, modal mineralogy and porosity.
  • Fluid inclusion studies: The laboratories have the capability for undertaking microthermometric and microchemical analysis of fluid inclusions, in support of investigations into rock-water interaction, fluid evolution, diagenesis, mineralisation, mineral exploration and the behaviour of fluids (hydrothermal, hydrocarbon, groundwater, gases) in the Earth’s crust.
    Analytical equipment includes: a modern Linkam digital heating-freezing stage for microthermometric fluid inclusion analysis; and determination of fluid composition, stable isotope fluid analysis, and ultra-trace elements in individual inclusions by Laser-Ablation ICP-MS. We can also undertake specialised crush-leaching analysis to determine bulk chemical composition of fluid inclusions in mineral samples.

Access to facilities for laser Raman spectrometry; PVTX modelling are also available.

  • Training Staff in the Petrography, Microscopy and Microanalysis laboratories are available to provide training in mineralogy and petrology analytical techniques, both in the UK laboratories and through visits by specialised staff overseas and to other off-site locations. We offer a consultancy and advisory service on setting up and operating laboratories together with training workshops for developing industries. Enquiries regarding training provision and opportunities are welcomed.
  • University collaboration The facilities have a successful programme of collaboration with universities through NERC, EPSRC and commissioned research projects, and through a number of M.Sc. and Ph.D. student projects. This involves both projects co-supervised by research staff within the laboratories, and provision of analytical support to projects supervised through other areas of BGS. Recent examples include collaboration with the University of Loughborough (environmental geochemistry M.Sc. projects, engineering geology), University of Leicester (gas hydrate research, engineering geology, planetary research), University of Edinburgh (palaeohydrogeology, CO2 sequestration), University of Cardiff (ophiolites research and geological mapping in the United Arab Emirates), University of Cranfield (BGS-co-funded Ph.D. project on carbonate formation in soils), University of Birmingham (engineering geology) and University of Nottingham (engineering geology)
Applications

The Petrography, Microscopy and Microanalysis Laboratories at Keyworth play a key role in projects that span the BGS science programme, providing fundamental mineralogical, petrological and geochemical information that underpins research in these areas. Examples include:

  • Background petrological and petrographical support to both national and international mapping projects (e.g. geological mapping of the United Arab Emirates, Madagascar).
  • Research in rock-water interaction and the investigation and characterisation of palaeofluids (hydrocarbons, hydrothermal fluids and groundwater) in the Earth’s crust.
  • Hydrogeological and palaeohydrogeological research, including petrographical and mineralogical characterisation of aquifer and aquitard systems and investigation of the impacts of Quaternary climate change on groundwater systems. (See also Environment and Health, Radioactive Waste Team, Climate Change, Groundwater Resources, BGS-hosted PADAMOT Website).
  • Provision of high-quality mineralogical, petrological and geochemical research and analyses for site investigations for the geological disposal of radioactive waste for UK and international clients, including Environment Agency (EA), Nuclear Decommissioning Agency (NDA) and United Kingdom Atomic Energy Agency (UKAEA), NAGRA (Switzerland), SKB (Sweden), JAEA (Japan), ANDRA (France), RWMC (Japan), Mitsubishi Corporation. (See also Radioactive Waste Team).
  • Provision of high-quality mineralogical, petrological and geochemical information on soils, waste materials and aquifer systems, to support research on environmental pollution, contaminated land and geochemistry of health. (See also Environment and Health).
  • Petrographical analysis and investigations of diagenesis in hydrocarbon reservoir and source rocks for the oil and gas industry.
  • Mineralogical and petrographical characterisation of the interaction of CO2 with reservoir and gap rocks, and borehole infrastructure for CO2 sequestration research.
  • Evaluation of mineral deposits and metallogenesis. (See also Minerals).
  • Petrographical and mineralogical characterisation of rock and soil fabrics in relation to their influence on engineering properties. (See also Land Use and Development).

Highly experienced staff and facilities undertake consultancy analysis and interpretation by UK and international clients including: radioactive waste management companies, environmental consultancies, hydrocarbons and energy industry and industry, mineral and mining companies, engineering and utility companies, consultancies, government agencies, university departments and local authorities.

For further information, please contact:

A E Milodowski
Mineralogy and Petrology Laboratories
British Geological Survey
Keyworth
Nottingham NG12 5GG
Tel: 0115 936 3548