Analogs

Geologists are all about analogs. Since we don’t have actual time machines, we have to look at modern situations to project into the past and determine what happened.

In a previous post I mentioned gypsum in Oklahoma, precipitating out of seawater on a hot, arid equatorial coastline 255 million years ago. A good modern analog for this is Umm Sa'id Sabkha, on the east coast of Qatar along the Persian Gulf (or Arabian Gulf if you prefer), in the photo below.

A sabkha (Arabic for salt flat) is a low-lying area occasionally inundated by marine water. When the water withdraws, mineral salts precipitate as the water evaporates. Sabkas are the basis for our understanding of how many ancient deposits of evaporite minerals formed, including salt (halite), gypsum (used in wallboard), and sylvite (a source of potash for fertilizer, mined in New Mexico and imported from Canada and Belarus).

Another analog: We’ve only known about black smokers (photo, left) since 1977. These hydrothermal vents on the abyssal sea floor spew superheated, metal-rich water into the ocean. Metal sulfides precipitate around the vents and provide a possible analog for ancient copper, lead, and zinc deposits exploited on land today. Deep mantle sources may be the origin of some metal concentrations in the crust.

Lots of mineral deposits can’t be explained by direct analogs—for example, we can’t really look at the roots of a modern volcano to observe the processes that may be concentrating ores there. But inferences from modern situations are probably the best way we have of understanding unusual mineral bodies and predicting where to find more.

“The present is the key to the past” – a concept first clearly expressed by Scottish geologist James Hutton in 1795 (but probably not in those exact words).

Images – Sabkha NASA, black smoker NOAA

Who’s got the oil in the US?

Perhaps it’ll surprise you to learn that thirty-one states have at least a little oil production. That leaves 19 with none at all. In most states with no oil production, there’s also little or no oil potential, just because the rocks there lack the properties for generating and trapping oil.

From the list below of non-producing states, those with some potential include most of the southern Atlantic seaboard – Georgia, South Carolina, and North Carolina. Oil accumulations may exist in sedimentary troughs in those states, as well as offshore, but exploration to date is not encouraging, so we’d call the potential pretty low there.

Volcanic rocks cover much of Washington and Oregon. That doesn’t make oil pools impossible, but the likelihood declines greatly. Most of Minnesota and Wisconsin are underlain by ancient rocks, a billion years and more old, from a time when life was limited mostly to single-celled organisms. You need teeming life to make petroleum, and even though much oil derives from single-celled life like algae, the amount of life a billion years ago was not enough to make oil – or if it did, it has not survived collisions, subductions, and other traumas the earth has thrown at the older rocks of Wisconsin. The younger rocks there are relatively thin, another factor reducing the potential for commercial oil fields. You need to bury organic material deeply to naturally cook it into oil, but not so deep as to overcook it.

So 31 states are awash in oil, getting rich on production taxes and severance taxes. Well, not quite. Almost 80% of US oil production comes from just four states. For November 2009 (data from World Oil), the four leading states in descending order were Louisiana, Texas, Alaska, and California. The other 27 producing states together account for just over 22% of total US oil.

Here’s the list of 19 states with no oil production at all in November 2009:

Connecticut, Delaware, Georgia, Hawaii, Idaho, Iowa, Maine, Maryland, Massachusetts, Minnesota, New Hampshire, New Jersey, North Carolina, Oregon, Rhode Island, South Carolina, Vermont, Washington, and Wisconsin.

The map below, from the US Geological Survey, shows most of the wells in the US – more than 500,000 producing oil wells (over half the oil wells on earth), plus gas wells and dry holes. Some estimates figure three to five million wells have been drilled in the US in the search for oil and gas.

Cooking, cleaning, cooling

Fluorine is another relatively obscure element, but one virtually every American has in his or her home.

Fluorine gas derives mostly from the mineral fluorite—a beautiful mineral, prized by collectors for its multicolored cubic crystals. The Cave-in-Rock District, along the Ohio River in southern Illinois, once produced most of the world’s fluorite (also known as fluorspar). Those mines are closed now, and the U.S. is dependent on imports for 100% of the fluorspar that we consume, amounting to more than 400,000 tons each year.

Where does it go? Most fluorine goes to make hydrofluoric acid, critical in aluminum and uranium processing. And hydrofluoric acid is the feedstock for all fluorine-bearing chemicals, and this is where fluorine ends up in homes.

Teflon in non-stick cookware and Freon in air-conditioning systems are brand names for fluorinated compounds. Then there’s fluoride in toothpaste and municipal water systems, not as a communist plot but to alleviate tooth decay because fluorine in the crystal structure of calcium phosphate (the mineral making bones and teeth) is stronger than otherwise.

Enamel coating your stove almost certainly contains fluorine. Glass and steel manufacture demand it, as does cement production.

Where does the U.S. get fluorspar? Most imports (52% in recent years) come from world production leader China. Another 34% is imported from Mexico, with South Africa a distant third as a U.S. fluorspar supplier.

Photo of fluorite from Cave-in-Rock by Richard Gibson

Disclosure

This probably doesn’t apply to me, but just in case.

The Federal Trade Commission requires bloggers to disclose any freebies or promotions they get in connection with any products they discuss.

So:

No one gives me anything. Well, sometimes a friend of relative does, but I’m not endorsing them, either. I don’t get any kickbacks from the government of China for describing the Bayan Obo rare-earth deposit. Toyota isn’t breaking down my garage door to give me a Prius because I talk about the neodymium in its motor or the lithium in its battery. In case that should happen, I’ll be very happy to disclose the fact.

My goal is to be objective anyway, so if a company gave me a freebie, that wouldn’t guarantee much, anyhow.

Good enough?

Toast for breakfast

How many nations do you depend on when you toast your morning bread?

My cheap $15 toaster’s case is mostly galvanized (zinc-coated) steel, with white exterior surfaces thanks to a thin enamel covering. Common traditional toasters, many still in service, are chrome-plated steel. The ends of mine are white plastic with red lettering.

The bread rack inside is also chrome- or nickel-plated steel, although in mine there’s also an aluminum support system. Stainless-steel (a chromium-iron alloy) screws and rivets hold the whole thing together. A nickel-chromium alloy, in strips wrapped around a mica sheet or mica-paper board, does the work. Nickel-chromium has high electrical resistance—it doesn’t conduct electricity well, so when a current flows through it, it gets hot.

Differential thermal conductivity comes into play again, in the thermostat, which may be a simple bi-metallic strip (usually steel and copper). The two metals heat up at different rates, forcing the strip to bend. This action in turn effectively flips a switch to turn off the heat and release the rack so it pops up.

The wire that leads to the electric outlet is copper, insulated by flexible plastic.

Some of the raw materials that make the toaster come from domestic mining, but the U.S. depends on imports for most of the materials.

Bauxite (aluminum ore) – 100% dependent (from Jamaica, Brazil, Guinea, and 5 others)
Nickel – recycling + imports = 72% (from Canada, Russia, Norway, and 18 other countries)
Chromium – recycling + imports = 100% (from South Africa, Kazakhstan, and 12 other countries)
Mica – 16% (from Canada, China, India)
Oil and refined products for plastics – 58% (Canada, Mexico, Venezuela, Saudi Arabia, and 64 other countries)
Titanium dioxide pigment – U.S. exports, but depends on 77% imports for titanium metal (South Africa, Australia)
Antimony (flame retardant in plastic) – 86% dependent (China)
Copper – 33% to 43% dependent (from Chile, Canada, Peru, and 12 others)
Zinc for galvanizing iron – 73% dependent for zinc metal (Canada, Mexico, Korea)
Iron ore – U.S. just about breaks even: a small exporter some years, a small importer in other years.

We’ll save the bread itself, together with the electricity to run the toaster, for future posts.

So how many countries in your toaster? Canada, India, South Africa, Russia, Norway, Mexico, Kazakhstan, Chile, China, Jamaica and the U.S. – eleven countries at a minimum.

Photo by Donovan Govan, used under the GNU Free Documentation License.

Consider the fork

Perhaps your family heirloom cutlery is sterling silver (that is, 92.5% by weight silver and 7.5% copper), but most likely your “silverware” consists of stainless steel.

Stainless steel has been around for only about 100 years, although chromium’s corrosion resistance in iron alloys was known by the 1820s. In the 1910s metallurgists invented ways of reducing chromium’s carbon content to make commercial stainless steel possible. Chromium makes steel “stainless,” not literally true, but such alloys are far less likely to rust.

Chromium finds its greatest use in stainless steel alloys, but dinnerware represents a tiny portion of end use. Structural elements in cars, aircraft, and appliances, together with building construction, take huge volumes of stainless steel. Most stainless steel alloys contain 10% or more chromium, with iron proportions at 70% to 90%.

While iron and chromium dominate the chemistry of stainless steel, your knife or fork probably contains other metals that make the alloy more machinable, resistant to abrasion, or simply more shiny. Nickel, manganese, molybdenum, titanium, and aluminum all contribute desirable properties to stainless steel. Dinnerware alloys commonly contain nickel (10%) and chromium (18%) combined with iron (72%). Nickel makes the alloy stronger, and chromium increases hardness along with its corrosion resistance.

The U.S. has no primary chromite (iron-magnesium chromate, (Fe,Mg) Cr2O4, chromium’s principal ore) production from mines, but our import dependency is only 39% thanks to a remarkable 61% of supply generated by recycling. Imports come mainly from South Africa and Kazakhstan, which together with India produce three-quarters of the world’s chromium—one of few elements whose production isn’t dominated by China.

Chromium metal hit record prices in 2008, averaging $11,078 per ton. U.S chromium consumption is declining with the recession, but in 2008 we used more than 400,000 tons worth more than $1 billion. With prices like that, it’s no surprise that one chromite deposit about 10 miles south of Coos Bay, Oregon, is being evaluated and permitting is in the works. Additional chromite reserves exist in the 2.7-billion-year-old Stillwater Complex of south-central Montana.

My battle with “of”

I think scientists generally put lots of “ofs” in their writing. At least I do. I know it, I hate it, and I still do it.

Combined with the discovery of the vast copper resources of Chile, this spelled the beginning of the demise of the copper business of the United States. 

One of my first editors, my friend Sally Lawrence, read that line (and the plethora of other prepositions I had peppered my prose with) and wrote “Oh woe is me—prepositions are the downfall of many a good geologist.” I find now that I must force Word to highlight all my “ofs” so that I can ruthlessly, tediously reduce their number. I have trouble avoiding the word: I’m so accustomed to writing things like “the geology of Canada contributed to its position as one of the world’s leaders in production of mineral resources” – yikes! When I see that now, I really cringe! (But only when I’m on alert, in editor mode, and watching for such literary atrocities.)

But at least overuse of “of” can be repaired. Or maybe I should lose the “ofs” and say “I can overcome this problem.” Sometimes.

I’m prone to happily split an infinitive here and there, and I agree with Winston Churchill’s lines ending in prepositions, at least occasionally. And “of” is a useful and necessary word. I’m just trying aggressively to improve my writing by controlling its unchecked spread.

I hope you like the revised sentence about Chile’s copper. It may not be perfect, but at least it’s a little better, I think!

Combined with vast copper discoveries in Chile, decreased demand drove the U.S. copper industry into a long, generally downward spiral.