Electron Microscopy and Spectroscopy

BEG e-MAGE Lab

The BEG’s advanced Electron Microscopic Analysis in Geology and Engineering (e-MAGE) Laboratory specializes in chemical and textural microanalyses of natural and engineered samples. The SEM facility is equipped with state-of-the-art imaging, analytical, and sample preparation capabilities.

Equipment Includes:

**Zeiss Sigma Field Emission Scanning Electron Microscope** equipped with large-area Gatan SEM-cathodoluminescence (panchromatic, RGB color, and CL-spectrometry) and advanced EDS elemental mapping for compositional, textural, and diagenetic characterization.

**Hitachi SU-8700 Field Emission Scanning Electron Microscope** equipped with ultrafast large-area microanalytical capabilities using AMICS (Automated Mineral Identification and Characterization System) and Delmic Cathodoluminescence Detector to understand rock provenance and diagenesis.

Automated mineralogy software **AMICS** allows for fast identification of mineral phases, textures, and spatial distributions over a selected area on mounts or thin sections (red rectangle, top right image) using a comprehensive reference database compiled by the American Mineralogical Association. This example is from the Fei di Doccio lower crustal magmatic sulfide deposit in the Ivrea-Verbano Zone in Italy. Understanding the sample mineralogy and deportment of critical minerals in different mineral phases is pivotal for informing mineral extraction flowsheet development.

Specialized Imaging Technique: SEM-Cathodoluminescence

SEM-cathodoluminescence (SEM-CL) is the emission of photons of characteristic wavelengths from a material under high-energy electron bombardment as a function of composition, trace elements, and lattice structure defects. SEM-CL provides information unavailable through other known imaging techniques including detrital grains versus cements, different generations and textures of cements, deformation mechanisms and relationships, and types of porosity including nano- and secondary.

(A) Secondary electron SEM image of quartz grain. (B) Panchromatic SEM-CL image of the same area showing multiple fracturing and cementation events invisible using SE or optical imaging.

SEM-CL data combined with advanced Elemental Dispersive X-ray Spectroscopy (EDS) provides quantitative diagenetic and microstructural information that can be used for model input or validation.

Combining SEM-CL with EDS allows for identification of porosity, bulk mineralogy, and cement compositions and textures. In this example from the Zeiss Sigma SEM, porosity (black) is mostly retained within the central cataclastic deformation band rather than the surrounding undeformed host rock due to multiple generations of authigenic calcite cement (blue) in primary pores.

e-MAGE Sample Preparation Equipment

Zeiss-Axio Camera Imager.A2m automated stage Optical Microscope
2 Argon-Ion millers
2 Carbon coaters
Iridium coater
Saw, Polishing wheel, Sonicator, Oven

e-MAGE Lab ArcGIS SEM Petrography Database

The BEG e-MAGE Lab has created an ArcGIS-based SEM petrography database designed to make high-value imaging and quantitative petrographic data publicly visible, reusable, and collaboration-ready for internal and external interest groups and users. This is a multi-year initiative to capture, QC, and summarize legacy archives, with Phase 1 available here: https://arcg.is/1faOje3

The current platform is a prototype containing ~10% of our archive data. It is enough to demonstrate the structure, search power, and workflow while we continue scaling toward a comprehensive database and eventually building links to all raw images.

At its core, the system is a structured, searchable catalog of SEM-related datasets organized by formation, depth, geologic age, and data type. Users can filter and browse by:

(1) Formation / stratigraphic unit and basin/play context
(2) Depth and sampling interval
(3) Geologic age / stratigraphic framework
(4) Data type: SEM-SE, BSE, EDS maps, CL, AMICS/QEMSCAN-style mineral maps, experiments, derived products
(5) Image coverage: fields of view, mosaics, map extents, resolutions
(6) Associated publications and reports

Beyond imagery, the database supports quantitative petrography using standardized workflows (e.g., point counting, pore tracing, image-based measurements). All the metadata is validated and confirmed using S&P Global.

EPS E-beam Lab

The Department of Earth and Planetary Sciences (EPS) E-beam Laboratory specializes in spectroscopic analyses of mineral phases and major element compositions.

Equipment includes:

JEOL JXA-8200 Electron Microprobe (EPMA) – Equipped with 5 wavelength dispersive spectrometers (WDS), secondary electron (SE), and backscattered electron (BSE) detectors.
JEOL 6490 Low-Vac Scanning Electron Microscope – Equipped with electron-backscatter diffraction (EBSD), secondary electron (SE), backscattered electron (BSE), cathodoluminescence (CL), and energy-dispersive X-ray (EDS) detectors.
Bruker D8 Advance Powder X-ray Diffractometer (XRD) – Provides routine, qualitative mineral identification and semi-quantitative modal mineralogy in rock powders.
Raman Spectrometer
Fourier Transform Infrared Spectrometer (FTIR)

Bruker D8 Advance Powder X-ray Diffractometer

TMI Electron Microscopy Facility

The Texas Materials Institute EM facility provides state-of-the-art sample preparation and atomic scale characterization instrumentation including TEM, FIB:SEM, SEM, STEM, and ESEM. The facility consists of a suite of specially designed low-vibration rooms with precise temperature and humidity control. Operation of TEM is done remotely in a separate room to remove the impact of people on the room stability. An array of specialized holders and detectors are available for state of the art in-situ capabilities and imaging.

Equipment includes:

JEOL NEOARM Low kV STEM Corrected – Low-voltage, probe-corrected transmission electron microscope with aberration correction from 30 kV to 200 kV, equipped with atomic-level elemental mapping using EDXS and EELS, energy filtered imaging, electron binding state and plasma mapping, and in situ liquid cell, heating, and biasing.
Thermo Fisher Scios 2 HiVac Dual beam FIB:SEM – High quality TEM sample preparation with Sidewinder HT FIB, Easylift, and AutoTEM, subsurface and 3D characterization, high contrast UHR imaging with in-lense Trinity detection scheme, automated serial milling and imaging with Auto Slice and View 4.
FEI Quanta 650 ESEM – Three imaging modes: high-vacuum, low-vacuum, and environmental SEM (ESEM) which enables charge-free imaging and microanalysis of non-conductive specimens without preparation. Bruker EDX for chemical analysis and Quorum Cyro-stage for specimen imaging in “natural” hydrated state.
Hitachi S-5500 SEM/STEM – Capable of scanning transmission electron microscopy (STEM) mode at sub-nanometer resolution, Duo-STEM detector for simultaneous observation of bright field (BF) and dark field (DF) STEM images, equipped with energy dispersive spectroscopy (EDS) providing chemical composition of materials at nanometer scale.
Thermo Fisher Apreo 2C LoVac SEM – Low-vacuum imaging for charge-free imaging and analysis of non-conductive, outgassing, or beam-sensitive samples without metal coating.

Sample Preparation Equipment includes:

Hitachi Ozone Cleaner
EMS Sputter Coater
Leica Cryo Setup
Leica EM TIC 3X

Scios 2HiVac Dual beam FIB/SEM System with EBL Capabilities