How is a mineral of organic origin with large crystals most likely formed

Evaporation process

Explanation:

The larger crystals are often found to be present in association with other minerals that are comprised of organic origin. Initially, these minerals are saturated with water. With the increasing time and increase in the amount of heat supply, the water present in the solution gradually evaporates. This leaves behind only the concentration of organic mineral and the comparatively larger crystals, that accumulate and make it a mixed type of mineral. This is how the mineral of organic origin can be found in association with large crystals by the process of evaporation.