The thread was pointed out to me a couple days ago. I read it then.
So, without bothering to catch up with it, here are some
facts:
Coticule rock has, for various reasons, piqued the interest of geologist and mineralogist, and has been extensively submit to scientific research. Scientific papers have been submitted and approved for publication.
Some of them are available online in digitized format, albeit not all for free:
Alphonse Renard, "Sur la structure et la composition minéralogique du coticule et sur ses rapports avec le phyllade oligistifère", 1878 is one of the earliest studies known to me. It's in French. He describes in detail how the garnets look as examined with various microscopic techniques (polarized light, etc) under magnification of 600 to 800 X.
It was also Renard who coined the term "Coticule" in its scientific meaning:
See:
This link contains a study of a Coticule deposit in The Bahia Mansa Complex, CHILE. It contains some interesting pictures of garnets, as found in Coticules.
Another well-known paper is: "The Coticule Rocks (Spessartine Quartzites)of the Venn-Stavelot Massif,Ardennes, a Volcanoclastic Metasediment?", By Ulrich Kramm, published at Mineralogisch-Petrographisches Institut der Universitât Köln, Germany.
Also Kramm describes garnets, their sizes and composition. The paper is available through Springerlink:
It is not a free resource, but I have a copy:
There also exists a recent book about the topic of Coticules, written in French under the scientific direction of Dr Sc Eric Goemaere, geologist at the Geological Survey of Belgium - Royal Belgian Institute of Natural Sciences.
The book shows a very clear picture of a garnet as shown by a scanning electron microscope. It also elaborates about the composition of Coticules in detail. Another picture shows a large bunch of garnets as seen through a polarizing microscope. They are all smaller than 10 micron. There are the drawings Alphonse Renard made based on what he saw during his microscopic examinations: round and rhomboid shaped particles.
Apart from that, I don't care if they work with garnets or petrified droppings of a dinosaur.
I do regret the infantile innuendo towards the honesty of Ardennes Coticule about the product they sell.
Kind regards,
Bart.