colloform

Apparently from collo(id) +‎ -form.

colloform (comparative more colloform, superlative most colloform)

1. (mineralogy) Having a rounded, finely banded texture formed by rhythmic precipitation.
   • 1982, S. S. Augustithis, Atlas of the sphaeroidal textures and structures and their genetic significance:

     Often complex textural patterns of more than one colloform mineral phase might co-exist.

   • 2010, Stylianos Augustithis, Atlas of the Textural Patterns of Ore Minerals and Metallogenic Processes:

     As mentioned, the transition of colloform to crystalline structures is achieved mainly by the reversibility of gel to sol and possibly from sol to a solution phase out of which crystallization can take place.

   • 2012, Kula Misra, Understanding Mineral Deposits, page 106:

     The colloform ores, developed primarily in the open spaces of breccias and fractures, are inferred to be younger than disseminated ores on the basis of the following textural relationships […]

• mindat.org