Mention instances of concretionary formations.
Why may not these concretions have been deposited as nodules?
How have these concretions been formed?
Mention instances of segregation without the concretionary structure.
How was the segregation in these instances effected?
How is the columnar structure produced?
What is the origin of the mineral veins which are first mentioned?
How is it shown that other veins are not injected?
How were these veins formed?