[Rockhounds] Life Helps Make Almost Half of All Minerals on Earth

[Herwig Pelckmans]

Hi Linda,
I think the Mindat description for a geode is pretty good:
https://www.mindat.org/glossary/geode
Cheers, herwig

Op za 2 jul. 2022 om 20:03 schreef <linda at middleearthminerals.com>:

> This is totally consistent with many (possibly most?) geological
> definitions since they incorporate the formation process.  For example, a
> cirque is formed by the head of a glacier.  If it looks similar to a cirque
> but was not formed by a glacier, then it isn't truly a cirque.
>
> To bring it down to our interests, I believe even the humble geode
> requires a definition acknowledging formation.  If you don't consider
> formation, how do you exclude carved vugs, for example?  In my opinion, a
> geode can be exposed by carving if it could eventually have weathered out
> as an intact, roughly spherical unit.  This requires that it have some
> internal structure (often layers of quartz or agate) that produces a "rind"
> tough enough to keep it together while weathering out.  Geodes can form in
> both sedimentary and igneous environments.  (I even have one that may be
> metamorphic.)
>
> Why define a geode?  I used to exhibit at a county fair and had to guess
> at what the judges would consider a geode to be.  It turned out to be an
> intriguing and difficult definition.
>
> -----Original Message-----
> From: Rockhounds <rockhounds-bounces at rockhounds.drizzle.com> On Behalf Of
> Kreigh Tomaszewski
> Sent: Saturday, July 2, 2022 6:13 AM
> To: Rockhounds at drizzle.com: A mailing list for rock and gem collectors <
> rockhounds at rockhounds.drizzle.com>
> Subject: [Rockhounds] Life Helps Make Almost Half of All Minerals on Earth
>
> The impact of Earth’s geology on life is easy to see, with organisms
> adapting to environments as different as deserts, mountains, forests and
> oceans. The full impact of life on geology, however, can be easy to miss.
>
> A comprehensive new survey of our planet’s minerals now corrects that
> omission. Among its findings is evidence that about half of all mineral
> diversity is the direct or indirect result of living things and their
> byproducts. It’s a discovery that could provide valuable insights to
> scientists piecing together Earth’s complex geological history — and also
> to those searching for evidence of life beyond this world.
>
> In a pair of papers published today in American Mineralogist, researchers
> Robert Hazen, Shaunna Morrison and their collaborators outline a new
> taxonomic system for classifying minerals, one that places importance on
> precisely how minerals form, not just how they look. In so doing, their
> system acknowledges how Earth’s geological development and the evolution of
> life influence each other.
>
> Their new taxonomy, based on an algorithmic analysis of thousands of
> scientific papers, recognizes more than 10,500 different types of minerals.
> That’s almost twice as many as the roughly 5,800 mineral “species” in the
> classic taxonomy of the International Mineralogical Association, which
> focuses strictly on a mineral’s crystalline structure and chemical makeup.
>
> “That’s the classification system that’s been used for over 200 years, and
> the one that I grew up with and learned and studied and bought into,” said
> Hazen, a mineralogist at the Carnegie Institution for Science in
> Washington, D.C. To him, its fixation on mineral structure alone has long
> seemed like a monumental shortcoming.
>
>
> https://www.quantamagazine.org/life-helps-make-almost-half-of-all-minerals-20220701/
> _______________________________________________
> Rockhounds mailing list
> Subscription Services:
> http://rockhounds.drizzle.com/mailman/listinfo/rockhounds_rockhounds.drizzle.com
> List Usage Policy:
> http://Tomaszewski.net/Kreigh/Rockhounds/Rockhounds.shtml
>
>
>
> _______________________________________________
> Rockhounds mailing list
> Subscription Services:
> http://rockhounds.drizzle.com/mailman/listinfo/rockhounds_rockhounds.drizzle.com
> List Usage Policy:
> http://Tomaszewski.net/Kreigh/Rockhounds/Rockhounds.shtml
>