Here's how it works:

1. Burial: The dinosaur dies and is quickly buried in sediment like mud or sand.

2. Porous Bones: The bones of the dinosaur, though strong, are porous. They have tiny spaces within them.

3. Mineral-Rich Water: Groundwater, often rich in minerals like silica, calcite, or pyrite, seeps through the sediment.

4. Mineral Replacement: The minerals in the water slowly infiltrate the porous spaces within the bone. Over time, these minerals crystallize and replace the original organic material of the bone.

5. Fossil Formation: This process can preserve the original shape and even some of the internal structure of the bone, transforming it into a rock-like fossil.

So, in essence, permineralization is the process where minerals replace the organic material of a bone, turning it into a fossil.