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I am writing a mineral guide for smartphones which classifies minerals according to their formation environment.

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From sugestions on this related question, I changed the classification to:

  • Sedimentary
  • Magmatic Tardimagmatic
  • Metamorphic
  • Hydrothermal
  • Supergenic?? Exogenous

The question mark is because comments on other related question sugest supergenic would not be a good term to include weathering resulting minerals from igneous, sedimentary or metamorphic bodies on surface.

Would it be appropiated to classify weathering minerals as Superficial alteration. The first time I wrote the DB I refered it as Exogenous, but it looks no correct acording to answers on first linked question.

Just Weathering maybe? That would be acceptable on the US?

Edit

From @Fred answer and @Gimelist previous answer, I will finally classify them as:

  • Sedimentary
  • Magmatic
  • Metamorphic
  • Hydrothermal
  • Supergenic
  • Weathered

Thanks. I hoppe this is the best for my future users/students.

I will post a link to this on a page "about the classification", encouraging the students to join the site and ask their questions.

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    $\begingroup$ don't forget anthropogenic and biological minerals. also hydrothermal should probably just be chemical since there are a lot of hydro-chemically deposited minerals that don't need noticeable heat. you also may want to look at this. mindat.org $\endgroup$
    – John
    Commented Jan 21, 2020 at 13:57
  • $\begingroup$ @John my list has 180 common minerals on geological process. It is true pyrite can be ss biogenical but I mention it if you see the picture. Sedimentary: Early diagenesis of reductive environments. Bacterial origin, and for calcite I have Sedimentary: biogenic origin on shallow and intermediate marine basins. Chemical precipitation on river and lakes. I have not antrophogenic minerals on my list and I can classify biogenic cases as sedimentary including in the description they are biogenic. $\endgroup$
    – user18590
    Commented Jan 22, 2020 at 20:27

2 Answers 2

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My understanding of supergene is that it is about mineral enrichment/concentration at the base of an oxidized zone, within a weathered profile. The seasonal/periodic rise and fall of the local water table is critical to supergene enrichment.

The descending meteoric waters oxidize the primary (hypogene) sulfide ore minerals and redistribute the metallic ore elements. Supergene enrichment occurs at the base of the oxidized portion of an ore deposit.

Supergene would not apply to the top of a weathered zone but to the base.

My old geology dictionary (The Penguin Dictionary of Geology, 1979) describes supergene as:

A word suggesting an origin literally 'from above'. It is used almost exclusively for processes involving water, with or without dissolved material, percolating down from the surface. Typical supergene processes are solution, hydration, oxidation, deposition from solution, reactions of ions in solution with ions in existing minerals.

To me, supergene has a specific meaning, it may be part of the weathering process in some locations, but weathering involves the breaking down of rocks due to: reactions with atmospheric gasses, water (usually rain), changes brought on by plants, bacteria wind and temperature.

My suggestion to use the term weathering or weathered.

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I don't see anything wrong with Supergenic. It is widely understood and includes weathering. I would stick to Supergenic if I were you. You probably realise that there are some rocks which, as they are produced in more than one way, would fit into several of your classification headings. There is no way of avoiding this. Quartz, for example, can be magmatic, metamorphic, sedimentary or hydrothermal.

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  • $\begingroup$ This is important because I am creating questions with code like "In wich environment would you find hematite? a)Supergenic b)...." I calculate not to show two correct options on the test. So do you think it is correct to say hematite forms as supergenic on supergenic enrichmetn ores, and eg illite is supergenic because it is a weathering product? That simplifies my DB. $\endgroup$
    – user18590
    Commented Jan 21, 2020 at 19:47
  • $\begingroup$ Haematite can form in a number of ways and fits several of your classification headings, including Supergenic. $\endgroup$
    – Michael Walsby
    Commented Jan 21, 2020 at 19:56
  • $\begingroup$ Yes. I consider that on questions generation not to show two correct options. I appreciate your answer but gonna follow Fred advice and separate weathering minerals from those formed on enrichment supergenic ores. $\endgroup$
    – user18590
    Commented Jan 22, 2020 at 11:27

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