A 3D scanning technique that images the location and size of iron-oxide grains for Micromagnetic Tomography. MicroCT stands for micro X-ray computed tomography. It works by subjecting a sample to X-rays, where the transmitted X-rays are recorded by a X-ray detector behind the sample. After subjecting the sample to X-rays in one direction, the sample is slightly rotated and the procedure is repeated. The results obtained by these detectors is inverted for a planar density distribution within the sample. By combining all different scans, this planar density distribution can be converted into a 3D image. Then the grains with a density matching that of iron-oxides are picked and used in the next step of MMT.

MicroCT is a non-destructive technique, which means that the sample is not altered or destroyed by during X-ray scanning. This makes MicroCT of vital important for MMT, which has as goal to infer paleomagnetic properties from rock samples in a non-destructive way. The resolution of a MicroCT can be as small as hundreds of nanometers.