The 366 daily episodes in 2014 were chronological snapshots of earth history, beginning with the Precambrian in January and on to the Cenozoic in December. You can find them all in the index in the right sidebar. Now, 2015, the blog/podcast is on a 3 or 4 per month schedule with diverse topics.

Monday, March 23, 2015

Episode 370: Pseudomorphs

Malachite pseudomorph after cuprite showing octagon and dodecahedron faces.
From Chessy, France. Specimen is just over 1 cm in maximum dimension.
Photo by Richard I. Gibson.
Today for Mineral Monday my special guest is Kyle Eastman, mineral collector and geologist, here to discuss with me some special minerals called pseudomorphs. These are “false form” minerals that have the shape of one mineral but are actually something else because of replacement, substitution, encrustation, or some other process.

We discuss some classic pseudos from Chessy, France and Corocoro, Bolivia, as well as one of Kyle’s favorite skarns from Arizona.

Running time, 19 minutes.
—Richard I. Gibson

Thursday, March 12, 2015

The Mineral Episodes

This episode is a package containing all the previous episodes of the podcast related to minerals and mineral deposits. There are 16 of them, and the running time is about an hour and thirty minutes. Thanks very much for your interest.

—Richard I. Gibson

Wednesday, February 25, 2015

The Ordovician Episodes

Running time 2 hours 15 minutes

This episode is the third monthly package of the History of the Earth calendar. It combines the daily episodes for March 2014, covering the Ordovician Period of the Paleozoic Era.

You’ll find that I’ve left the references to specific dates in the podcast so that you can, if you want, go to the specific blog post that has links and illustrations for that episode. They are all indexed on the right-hand side of the blog.

As the year continues, there will be occasional new episodes in addition to these monthly assemblies.
If you have questions or comments, please let me know, either here on the blog – there’s a page for asking questions tabbed above – or contact me by email at rigibson at I’ll try to respond. You can of course also leave a review on iTunes. I really do appreciate your feedback.

—Richard I. Gibson