Wood and wood-based building materials are considered key elements of our future socio-economic environment. Wood is mainly used as a structural material, in building structure envelopes, and as insulation. Its biodegradability is an asset at the end of its service life, but also an important parameter to control to maintain a good product lifespan. Wood mineralization has attracted a great deal of interest in recent years in the field of wood modification. Compared to traditional wood modification processes, mineralization is a simple, environmentally friendly process that improves wood properties. Minerals are incorporated into the biological matrix of wood which increases the fire resistance. X-ray CT scanning is a non-destructive technique and can be used to visualize and quantify mineralization in 3D, to quantify the difference in mineralization in early- and latewood in spruce and beech wood blocks, the average penetration depth of mineralization, and the mineralization in different regions of the woodblocks. Spruce samples have the highest weight gain which is represented by a higher normalized mean grey value in X-ray CT scanning. In the longitudinal direction, all specimens show a mineralization gradient with a higher normalized mean grey value a few millimeters from the surface and a minimal value in the middle of the block. For spruce specimens, the mineralization occurred to a greater extent in the earlywood region than in the latewood region.