We haven’t seen much of the sky lately. I long for some clear, blue days! I know that sitting in a smoky cesspool is a lot better than evacuating or watching my community burn so I’m trying not to be too down. But, boy-howdy, it is foul out there:

If you aren’t tuned in to Purple Air, you should be. It is a network of air quality sensors that you can freely access via the internet or a mobile device. We can simply look outside and see that the air is horrible. But that’s the stuff you can see. There are lots of things we are breathing in that we cannot see. These are the really bad things. In fact, we often have days where the air quality looks fine but is actually not. Sometimes you see a slight “haze” which can be the result of high concentrations of really small particles.

The Purple Air sensors measure several things but the one of interest is abbreviated PM for “particulate matter.” In this case, size matters. The sensors measure particles less than 10 microns in diameter and particles less than 2.5 microns. (A micron is also called a micro-meter, which is 10^-6 or 0.000001 meters, about 0.00004 inches.)

It’s the PM 2.5 number that’s displayed. You can see that this morning the Yreka sensors show the local air quality to be very bad with numbers approaching 300. That means 300 micrograms per cubic meter (µg/m³) of air. Anything over 100 is a health concern. Here’s the scale:

Small particles are inhaled and deposit themselves on the lungs and from there enter the bloodstream. It almost doesn’t matter what the source of the particles is, the size is what makes them a problem. Wildfire smoke is a good source of particulate matter. Power plants and vehicle exhaust are also primary sources. These particles can be made of hundreds of different chemicals, including things like metals, and they spread indiscriminately. We’ve all sat around campfires and breathed in the smoke and not thought much about it. But this is like having a campfire in your tent with you at night and then carrying it around with you all day long. No one does that! So please don’t think that just because forests are “natural” that means that forest fires are good for your lungs. (Here’s a good article about the health effects of particulates.)

The EPA website has a good primer about particulate pollution. If you have N95 masks you might consider wearing them if you are going to be outdoors. They can help block some of the small (1-3 micron) stuff. Here’s a graphic to give you a sense of scale:

Stay safe out there and pray for rain, I suppose, or at least a good stiff wind to clean out the valley!

Ancient Greek and Roman cartographers described a place called Thule, the most northerly location known to them. Today we think they might have meant Scandinavia, Iceland, or perhaps the island groups like the Shetlands, Orkneys, or Faroes. Later the term Ultima Thule emerged and it came to mean anyplace far beyond the known world. I used to read Hal Foster’s comic strip Prince Valiant when I was a kid. Val, if you know the story, is from Thule.

Thulium (Tm) is a lanthanoid and with the exception of radioactive Promethium (Pm, #59) is the rarest of the so-called rare-earths. A mere 50 metric tons of thulia (thulium oxide, Tm₂O₃) is produced worldwide each year. The main source is monazite sand, a reddish-brown phosphate mineral found in placer deposits. Thulium is used in lasers and semiconductors.

Thulia was first isolated in 1879 by a Swedish chemist named Per Teodor Cleve. A pure sample of thulium metal was not prepared until 1911.

But not in a good way. Strontium, in its pure metallic form, is soft and silvery-white but tarnishes readily. It’s not found in nature except in compounds. Like its neighbors in columns 1 and 2 on the periodic table strontium is quite reactive. Humphry Davy first isolated it in 1807.

The primary isotope of strontium has 38 protons and 50 neutrons and thus an atomic mass of 88. A radioactive isotope of strontium, Sr-90 (52 protons), is a product of nuclear fission. Nuclear reactors are a source and the long half-life (29 years) makes it a serious high-level waste issue. Sr-90 is also in the fallout from atomic bombs.

Strontium sits right underneath calcium on the chart and is biochemically similar to this crucial, bone-building element. Sr-90 has a nasty habit of substituting itself for calcium in bones. Exposure to fallout can result in bone cancers and leukemia. Typically the Sr-90 is inhaled or ingested unknowingly. Fallout is composed of a large variety of particulate debris, much of which is too small to see. And soils and water tables can be contaminated miles from any blast as the fallout can be borne aloft by the winds.

Those of us born after the atomic testing of the 1950s and 1960s have radioactive isotopes in our bodies. Sr-90 would be a likely one. Fortunately the amounts of these materials are pretty small, and the major events since then (Three Mile Island, Chernobyl, Fukushima) were insignificant by comparison to the wanton and irresponsible testing after WWII.

Strontium was added to glass to block the X-rays produced by cathode-ray tubes. Those CRTs were common in the early computing days, but have since been replaced by newer technologies. Strontium compounds are used in fireworks, where they give off bright red colors. I remember well doing flame tests with my students and seeing the lovely scarlet hues produced by strontium chloride:

San Bernardino is the largest of the Golden State’s 58 counties. It’s twice the size (~20,000 square miles) of second-place Inyo (~10,000 sq. mi.). Inyo County, by the way, is about the same size as Massachusetts. Kern County comes in third place, roughly 8,000 square miles.

At the southeast edge of Kern county, abutting the San Bernardino County line, is the town of Boron. It sits on the western edge of the vast Mojave Desert. It’s about 85 miles east of the San Joaquin Valley metropolis of Bakersfield. SR-58 climbs from there over Tehachapi Pass to get to Boron. Continuing eastward you’ll cross the junction of US-395. Barstow and I-15 are forty miles away. South of Boron is Edwards Air Force Base and its massive dry lake bed landing strip.

Two thousand folks live in Boron. Once it was nowhere, and then it was somewhere. Prospectors discovered borax in the early part of the 20th century and that changed everything. A mining town was born. Today the open pit mine (owned by Rio Tinto) is the largest in California and supplies half the world’s borates.

You can visit the mine.

Sodium borate (Na₂H₂₀B₄O₁₇) aka “borax” is the primary ore. It was made famous by the 20 Mule Team brand of detergent additive. You’ve seen the iconic images of the wagon trains that hauled borax from mines in Death Valley to the railroad in Mojave:

Boron compounds have a huge number of applications. They are used in glasses, ceramics, flame retardants, fluxes, alloys, insecticides, adhesives, wood preservatives, lubricants, fertilizers, and much more. Elemental boron, a metalloid, is a neutron absorber and is used in nuclear reactor control rods. It is also an electron acceptor (or “p-type dopant”) and added to silicon-based semiconductors. Boron is also an essential nutrient for plants but it is not clear if boron is necessary in animal physiology.

About four million tonnes of boron minerals are produced annually.

I found this bit of wisdom at the end of today’s post on The Endeavour, a blog by John D. Cook:

There are no solutions, only trade-offs.

Cook is an applied mathematician and he was writing about scripting languages (a kind of computer programming language). Most of the stuff on Cook’s blog is way over my head but every once in a while I learn something. Ultimately he was discussing using tools to solve problems. One scripting language was small and specialized, the other was more “expressive” (his term), that is, it had more features and thus more power. But that also meant he had to make more choices, and that created more chances to make mistakes. It’s a trade-off—productivity vs. expressiveness.

The solution depends on the problem, or as Cook says, it’s a “matter of tasks and circumstances.” He’s writing about his work, and his little saying up there should best be understood in that context. But it seems to be much more general than that. I suspect we could apply Cook’s dictum to lots of things.

But as I like to say, all generalizations are untrue. Rules-of-thumb like “there are no solutions, only trade-offs” are useful. Handy, even. They can help steer our thinking. If we recognized that a non-trivial problem (something worth solving) might not be solvable that might make us more humble. Less rigid in our thinking. More open to listening, and trying things out. Just because a problem isn’t solvable doesn’t mean things can’t be made better.

The sulfide of the metalloid Antimony (Sb₂S₃) is called stibnite. It is also the primary ore. The word comes from Latin—stibium—and that’s the source of the elemental symbol. Antimony is mined with other sulfides like cinnabar (mercury sulfide, HgS) and is found with gold, silver, lead, copper, arsenic, tungsten and many other minerals.

There was a domestic source of antimony: the Stibnite Mining Area near the town of Yellow Pine, Idaho. It’s part of the East Fork South Fork Salmon River (EFSFSR) watershed. It’s now a Superfund site. The USGS had this map:

It’s hard to get a sense of where this place is so here’s another map:

The town of Yellow Pine and the Stibnite Mining Area are near the “Mid” of the map label “Mid Fk Salmon R.” or about 80 miles west of Salmon. It is rugged, mountainous country and hard to get to but it is a popular area for rafting, fishing, and other recreation. Not to mention its forests and wilderness areas help protect a vast watershed.

Here’s a quote from the an EPA report on the site:

Past mining activities have deposited metals, spent and neutralized ore, waste rock, and mine tailings over half of the site. Mining-related source areas of potential contaminants include the Bradley tailings (the main deposition area), the smelter process area and its waste piles, process ponds, five heap-leach pads, unmaintained mine tunnel adits, and an open-pit mine. Contaminants associated with mining operations include heavy metals (e.g., arsenic and antimony) and cyanide in area soil, groundwater, surface water, seeps/springs, and sediments.

Mining is a messy business. Antimony is used in alloys, particularly in lead-acid batteries which are manufactured by the millions. It is also used in semiconductors. So, we need the stuff. And we need to figure out how to get the minerals we use without making a toxic waste dump that needs Superfund status!

Perpetua Resources (formerly Midas Gold, stock symbol PPTA) is an Idaho company and it has a plan to resume gold mining in the Yellow Pine/Stibnite Region. They also want to start producing antimony again.

The forks of the Salmon River eventually merge and then dump into the Snake River which is ultimately swallowed by the Columbia River. That runs all the way to the Pacific Ocean. I started my search for antimony and wound up with watersheds. All of us depend on the health of our watershed. If we poison our water upstream then that poison will show up downstream.

What watershed do you live in? Where does your water come from? Where does it go?

Do you know?

I remember when I was a boy my dad showing me a galvanized nail. He told me it had a zinc coating to protect against rust. About half of all the zinc mined today is used for galvanization. Perhaps better known is the alloy brass which is a mixture of copper and zinc. Bronze, an alloy of copper and tin, can include a little zinc in the mix. A large number of specialized industrial alloys contain a small percentage of zinc.

Zinc is an essential nutrient. You need 10-15 milligrams per day. In well-fed areas we get plenty from our diet. Zinc deficiency is a serious problem in malnourished regions.

Zinc makes a good anode and is used in alkaline batteries as well as the older zinc-carbon cells. Batteries are crucially important in the transition to renewable energy. We are going to need all kinds of batteries.

Worldwide about 13 million tonnes of zinc are produced annually. Only three other metals are produced in greater numbers—iron, aluminum, and copper. Zinc mining and smelting are very messy processes and the environmental and public health impacts are big. Lead and cadmium are often found along with zinc and both are considered toxic heavy metals.

Teck Resources Limited is a Canadian mining company. They own Red Dog in Alaska which is one of the largest zinc operations in the world. Here’s a picture:

It’s pretty far away. Here’s a rough map so you can get the idea:

Despite the name the rare-earth elements (lanthanoids) aren’t all that rare. Many are more abundant than well-known metals. But they are hard to get at. They aren’t concentrated in big ore bodies. Rather, the rare-earths are disseminated widely, in many rock types, and moreover are very similar to each other chemically. That makes them hard to separate. Many weren’t isolated until late last century.

The Greek word dysprositos means “hard to get at.” The chemist who first identified the metal (Paul Émile Lecoq de Boisbaudran in 1886) coined the name.

Seventeen elements are lumped under the REE banner:

Despite the relatively high crustal abundance REEs are not produced on the same scale as copper or lead:

TREO means Total Rare Earth Oxides which is how the global trade is measured (in metric tons).

These days the rare-earths are in the news. They have a lot of applications in the high-tech world we now inhabit. Fortunately we only need small amounts—compared to the massive amounts of copper we need, that is. But demand is going up. Most of the REEs are mined in China. There’s a mine in California (Mountain Pass) that has produced REEs in the past and has re-started operations. There’s a lot of interest in new domestic supplies and new processing plants.

Only 100 tonnes of dysprosium is produced each year. Neodymium magnets used in electric vehicle motors benefit from a small amount of dysprosium thus we will need more and more of the stuff going forward.

The six Apollo missions that landed on the moon brought back a total of 382 kilograms of lunar surface material.

That’s 842 pounds.

There’s a mine in Chile called Escondida. It’s the largest copper mine in the world. It routinely produces more than a 1000 kilotonnes of copper annually.

That’s so many pounds it may not be worth calculating! Fortunately we have Wolfram Alpha and it says 2.2 x 10⁹ pounds.

That’s 2.2 billion (2,200,000,000) pounds!

Here’s a quote from CEO Sherry Duhe (Newcrest) about our need for mines:

The mining industry needs to bring online the equivalent of 17 more Escondidas, the world’s biggest copper mine, by 2050, to meet demand projections, she said as an example of the scale of the problem.

That’s true in general, even if hyperbolic, as we will certainly need lots of copper and other minerals. In response to the problem we get stuff from NASA saying we will be mining the moon in ten years.

That’s a bit fanciful for me. 842 pounds isn’t a lot of rock! Imagine the number of rocket launches it will take to establish even the tiniest of a semi-permanent habitable human “presence” on the moon let alone some kind of industrial infrastructure. We’ve got better rocket technology today but it is just an improvement over the same rockets that were launched in Apollo’s day. The physics hasn’t changed. There are no fundamental breakthroughs in the industry. And space is still utterly hostile to human life.

No, I think we’ll have to get that stuff right here on earth and in our own back yards.

p.s. Check out this NASA/JPL website “The Lunar Gold Rush” and the infographic supplied there by 911metallurgist if you want to get a sense of how speculative the entire moon-mining venture is.

Copper, like gold, has been used by humans for thousands of years. Bronze is an alloy of copper and tin and every schoolkid knows about the Bronze Age.

The Romans originally called it aes Cyprium or “metal of Cyprus” as that island (Kupros in Greek) was famed for its copper mines. The metal ultimately came to be called cuprum and that’s where we get the Cu symbol.

Here’s how they mine for copper today:

That’s an open pit copper mine in Utah that’s half a mile deep and two and one-half miles across. It is one of the oldest and most productive mines on the planet. It is called Kennecott and it is located in Bingham Canyon near Salt Lake City. Kennecott Utah Copper Corporation is the listed owner and they are wholly owned by Rio Tinto Group, one of the largest metals and mining outfits in the world. Rio Tinto was founded in 1873 and spans the globe with headquarters in both Melbourne and London.

Copper is actually an essential nutrient. You need a milligram or two daily. But we mine for copper in these massive pits because we can’t have a modern society without it. We are connected together by a vast electrical grid. Through this grid flows the blood of a technological civilization—electricity. Without this blood we are doomed. Copper wires are like the arteries in our bodies that channel life-giving blood to our organs and extremities. The electricity the wires provide to our homes and businesses and everywhere else is just as life-sustaining. We live in an electrical world. There is no going back. We aren’t suddenly going to adopt Amish ways.

That means big, messy holes in the ground. Let’s hope we are smart enough to do it right and not make too bad of a mess.

World demand for copper is about 28 million tonnes annually. Chile is the world’s leading producer.