What looks like many small white lines on this point are the remains of dirt along the fracture lines. This cannot be distinguished well in the photographs. The light used tended to make it look this way in photographs.
MY cleaning technic changed over time. In the beginning years ago I did not clean well, then I started using an old toothbrush to get every bit of dirt off. This allows the mineralization to be clearly seen. However recently I have started using my fingers under the water from the rain barrel which leaves some dirt and I am liking how it looks more and more.