Some mineral structures, for example, montmorillonite, are capable of including a variable amount of water without significant change to the mineral structure.

The color comes from the presence of nickel in the mineral structure for magnesium.

Tints of green also occur and are connected with copper substitutions in the mineral structure.

In the process, the coral organisms are killed, and only a porous mineral structure remains.

Maybe natural mineral structures, or perhaps some living creature like coral had secreted them.

The red color comes from iron oxide in their mineral structure.

Native element minerals are those elements that occur in nature in uncombined form with a distinct mineral structure.

There is a very tight distribution of size, which is not what you'd expect from random mineral structures.

I would be curious to know what the expected size distribution of mineral random structures would be.

His views on the subject were contested at the time, and have since been disproven, the so-called organism being now regarded as a mineral structure.