Euxinic - What does it mean?
Mineral Matters #563
Do you know what “euxinic” means? Have you even heard of it?
I hadn’t until I read it in a book that I got a few weeks ago. The book in question is “An Introduction to Economic Geology and its Environmental Impact” by Anthony M. Evans, published in 1997.
This is not the sort of book subject that most mineral collectors read, but it can be interesting and help you to understand the nature of the occurrence of minerals.
So, back to euxinic.
The term "euxinic" refers to a specific type of water body condition that is both anoxic (lacking in oxygen) and rich in hydrogen sulphide (H2S). This combination creates a toxic environment for most marine life. Euxinic conditions are typically found in deep, stagnant water bodies, such as the Black Sea, where there is limited water circulation and organic matter decomposes without oxygen, leading to the build up of hydrogen sulphide. These conditions are particularly interesting to geologists and palaeontologists because they can lead to excellent preservation of organic material and fossils. The lack of oxygen slows down the decay process, and the presence of hydrogen sulphide can even help in the mineralisation of organic tissues, offering a glimpse into ancient ecosystems and climatic conditions.
So what has that got to do with minerals?
Well apparently, these conditions may have been present in places when deposits such as the Permian Kupferschiefer of Germany and Poland, and the Zambian copper belt formed.
This is different to many other copper and base metal deposits, such as porphyry, sediment-hosted deposits, or volcanic-hosted massive sulphide deposits.
And here is one ultimate product of the euxinic environment. A copper phosphate mineral from the Zambian copper belt. A dark green (almost black) libethenite with a tiny amount of pale blue turquoise(?), another Hidden Collection specimen. 😁
Below: Libethenite (with a little turquoise?), from the 104 metre bench of the Mindola pit, Nkana Mine (Rokana Mine), Kitwe, Kitwe District, Copperbelt Province, Zambia. Width of view 6mm.
