X-ray computed microtomography, neutron tomography, optical microscopy, scanning electron microscopy and energy dispersive X-ray spectroscopy data obtained using stromatolite samples from the Mbuji-Mayi Supergroup, Democratic Republic of the Congo

X-ray μCT data were acquired using a ZEISS VERSA 520 CT instrument at the NHM operating at a voltage of 120 kV with a beam current of 83.33 µA and power of 10 W. 1601 projections were acquired. The exposure time ranged from 2.0 to 2.7 seconds. Between 1015 and 1017 slices were produced during reconstruction, with a slice width of 1004 pixels and height of 1024 pixels. Tomograms were acquired at 5.64–8.25 µm/pixel. X-ray µCT datasets are named "KH_V..." with the sample name following. Neutron tomography was conducted at the IMAT beamline (ISIS Muon and Neutron Source, Harwell Science and Innovation Campus, Oxfordshire, UK). Each sample was imaged using the ANDOR iKon-L 936 CCD camera setup coupled with a 135 mm lens and a 60 µm thick LiF+ZnS scintillator sheet as neutron converter, providing a pixel size of 31.4 µm for a field of view of approximately 65×65 mm2. Each scan acquired 352 projections over 360° (using a 1.0256° step size), with 120 s exposure time per projection. The spatial resolution provided by this setup was approximately 60 µm/pixel in all datasets. Neutron tomography datasets are named "V..._Recon" with the sample name at the start. For ease of download, X-ray µCT and neutron tomography datasets have been compressed as .zip files. Optical microscopy was performed using an Olympus BX63 microscope (Natural History Museum, London) equipped with 2×, 5×, 10×, 20×, and 40× objectives in plane polarized light (PPL). Images of thin sections were acquired and assembled as mosaics using Nikon CellSens software. Optical microscopy images are provided as .png files. Hand sample photographs and optical microscopy images are provided as files named "V..." with the sample name at the start. SEM-EDS analyses were performed using JEOL JSM-IT500 variable pressure SEM equipped with an Oxford Instruments X-Max EDS detector (Natural History Museum, London). EDS maps were acquired at an accelerating voltage of 15 kV for 60 minutes and at a working distance of 10 mm. Data were acquired and processed using AZtec software (Oxford Instruments). SEM images and EDS elemental maps are provided as .png files. Electron images and elemental maps are provided as as files named "V..." with the sample name at the start followed by either "electron_image" or "[element symbol]".