Guest Video: Natural vs. Imitation New Mexican Turquoise


Turquoise made headlines recently when researchers discovered that Mesoamericans had more than one source for this gem that they valued highly. Not all of it came from the Southwest!

However, visitors to New Mexico and other parts of the American Southwest today do see a lot of turquoise. If you’re heading there on vacation, here is a video that shows you what to look for in a turquoise shop.




Featured image: Mr.TinDC, CC BY-ND 2.0


Arsenic: A Critical Mineral


This element is colorless, tasteless, inexpensive, and deadly–oh, and as a compound it can turn electricity into light (as in LEDs, fiber optics, telecommunication, and laser scanners).

That last “Star Trek”-style application is just one of the reasons why this “Murder She Wrote” element is on the 2018 US critical minerals list.

What is arsenic?

You might be thinking, wait, arsenic is a mineral? It’s not a nefarious white powder?

That powder exists, but it’s artificial. Arsenic itself is a metal–one of the weird ones that have a few nonmetal properties. As the chemical element As, it belongs in the same group of metalloids as antimony (Sb), another critical mineral.


Metalloid table image

The metalloids are green. Reading vertically, from top to bottom, arsenic is in group “15”–the nitrogen group–on the periodic table of elements. This matters for arsenic’s use as a semiconductor in electronics and telecommunications. (Links are live at image source.)


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Popocatepétl: A Dangerous Volcano


People in central Mexico have always felt a strong personal link with Popocatepétl, which they often call Don Goyo.

As we saw last time, when this volcano broke its five-decade silence with a VEI-2 bang in 1994, local people responded with traditional ceremonies; artists were drawn to the event; government officials took emergency measures; and scientists expanded their monitoring networks.

For almost a quarter of a century now, Don Goyo has been on center stage. People have adjusted to it and are moving on with their lives, as people always do after a natural disaster.

But scientists just updated the official hazard map (Spanish) for Popocatépetl, which we’re going to take a look at in this post.

The volcanologists did reassure everybody that there is no sign of any increased or upcoming increase in activity; the volcano is still at a “Yellow, Phase 2” alert level.

Also, to counter popular rumors, they stated in no uncertain terms that Don Goyo is not connected to Guatemala’s Fuego, which recently had a deadly eruption, or to Kilauea, out in Hawaii, with its spectacular lava flows. Each of these three volcanoes has its own plumbing system and exists for different geological reasons.

The problem with Popocatépetl is that, not only in 1994 but also at any point in modern times, this volcano has never shown the levels of violence that the geologic record proves that it is capable of.

And now Don Goyo has 25 million human neighbors, unfamiliar with its historic power and living less than 65 miles (100 km) away from its summit.

Ashfall risk from Popocatépetl


Ashfall risk for Popo

See CENAPRED’s hazard map (Spanish) for details. “Ciudad de México” is Mexico City.


  • The dotted line shows the area that would get at least 4 inches (10 cm) of ash if Don Goyo had another eruption as powerful as one about 14,000 years ago.
  • Red: In a big eruption, this unfortunate area could get lots of volcanic ash (up to yards/meters in depth) as well as a bombardment of rocks up to a foot (30 cm) in size.
  • Orange: Just a little ash would fall here in a small eruption, but up to 3 feet (1 meter) or more in a big one.
  • Yellow: This region isn’t at much risk of ashfall in small eruptions at Popocatepétl, but it could get several inches (dozens of centimeters) in a large eruption.

Seismic sensors, deformation monitoring, and gas/hydrothermal studies can pick up signs of such approaching events, especially the big ones.
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Guest Video: The Scottish Wildcat


Yes, a wildcat can be Scottish.

At least on my equipment, the perspective seems off on this video, but the information is so complete and well presented, based on what I’ve learned about this cat while working on the books, that I’m sharing it anyway.



PS, June 16, 2018: I have mixed feelings about the Scottish wildcat issue, but I am not expressing them here because they stem from reasons that are too complex to get into in just a thousand words or so. It must wait until I have been able to explain the basics of it in the upcoming ebook on the domestic cat, and its sequel on the modern cat family.

As anyone acquainted with a domestic cat might expect, even zoologists find Felis silvestris hard to deal with. One of the book chapters will mention this by focusing on the domestic cat’s scientific name: no one can agree on what it should be.

Wildcats are in the Felis silvestris group, but the scientific name for house cats is highly controversial–some say that it should be Felis silvestris catus, while others rightly point out that this is going to mess up a lot of environmental legislation meant to protect wildcats and therefore it should be Felis catus. But wait! say members of the first group. It is a wildcat descendant . . . and round and round the debate goes.

The Highland Tiger group is on the F. catus end of the opinion spectrum, but this video is a good introduction to the issue. My main concern, from this and from some scientific papers I have read, is two-fold:

  1. Hybridization is common in the cat family, so why should we draw the line between two close species now?
  2. How are they are going to handle feral cats? It is reassuring that many laypeople in the UK are aware of the feral cat issue and, from the looks of things, will not tolerate euthanasia–a too-easy out.

When first scheduling this guest video last week, I didn’t realize a note would be necessary, but on rewatching the thing today, I do want to make this addendum. Online resources on the Scottish wildcat issue generally are very polarized. I hope to add some neutral ground to the debate in the book chapter covering this.

Thank you for your interest!



Featured image: Peter Trimming, CC BY 2.0


Guest Videos: Dunhuang Yardang National Geopark


For today’s geopark, believe it or not, we need to start out on Mars!



“Yardang” doesn’t sound like a typical scientific term (in English, anyway), and it isn’t. It’s Ugyur for the same type of rock formation on Earth, and it was first used by geologists to describe these desert features near Dunhaung in China.

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Guest Video: Time Lapse Videos in 2016


We move too fast to see much of the movement made by this giant we live on and in, unless it has a spasm of some sort, like an earthquake, eruption, landslide, or storm.

None of us has the time to just stand around, watching the fascinating world around us. Fortunately, there are cameras.

So relax now for 16 minutes or so and let the sky roll over you (watch out for the snails and pity the ants, who live at an even faster pace than our own).



Antimony: A Critical Mineral




Look how careful these scientists are with that material!

And yet people in the past used it all the time:

  • Ancient Egyptians might have considered antimony strategically important, just as the US does today, but for different reasons. Instead of using it for batteries, flame retardants, synthetic materials, and military purposes, they made eyeliner with it.

    Screenshot_2018-06-10-15-24-50

    Nefertiti. (Arkadiy Etumyan, CC BY-SA 3.0)


  • The Arab word that Europeans first translated as “kohl” is al-kuhul, derived from kahala–to stain or paint. Medieval alchemists turned this into the Latin alcoholpowdered ore of antimony! They thought it would lead them first to something called philosophical mercury and then to the Philosopher’s Stone. “Alcohol” later came to mean any powder or liquid that remained after vaporization; the word didn’t acquire its boozy connotations until the 18th century, around the time that antimony was in use as a pigment again.

    Screenshot_2018-06-10-15-27-56

    Matthias Stom used antimony-based Naples Yellow in “The Arrest of Christ.” (Source)


It’s unclear if antimony harmed anyone back then, but it could have. While antimony’s effects on human health vary, it can cause liver, skin, respiratory, and/or cardiovascular problems.

Also, in some formulations antimony will burn (a feature that chemical experts have harnessed to provide us with green and white fireworks, as well as “glitter” effects).

Antimony is obviously a multipurpose (and sometimes sparkly) element. But why did the US government list it as a critical mineral in 2018?
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