The data were obtained with X-ray micro computed tomography instrument ZEISS Xradia 520 Versa. Xray source voltage was set to 40 kV. Transmitted X-rays were converted into visible light with a scintillator and magnified with a 40 ´ objective lens. The recorded pixel size was 0.33105 µm. The detector to sample distance was 22 mm. The X-ray source to sample distance was 20 mm. For each sample 801 X-ray transmission images were collected at the rotation axis angle spanning 360 degrees. These transmission image series were reconstructed into a three-dimensional tomographic datasets using the control software supplied with the instrument.