Earth's Mineral Wealth
October 19, 2015
Children enjoy collecting rocks. I collected rocks when I was young, as did my children when they were young, and I have one colleague who still has an interest in mineralogy. I learned the basics of geology at a very early age from several of my "Golden Books." That's how I learned to distinguish sedimentary from igneous from metamorphic, but I was always fuzzy about what a conglomerate was all about.
Rocks contain minerals, crystallites of simple chemical compounds. Since we live in an oxidizing environment, these minerals are usually oxides, sulfides, and sulphates. A few of the more common minerals are listed in the table below.
Humans have mined the Earth from prehistoric times looking for useful materials such as flint, for weapons, and hematite as a pigment. Thereafter, the more easily smelted metals, such as gold, silver, and copper, were mined for jewelry, cookware, weapons and armor. As I wrote in a previous article (Antimony Nanocrystals, April 7, 2014), the chemical extraction of metals was well developed quite a few centuries ago. In his 1556 book, "De Re Metallica," Georgius Agricola gave the following method for extraction of silver from gold by means of antimony (stibium).
Silver is also parted from gold by means of stibium. If in a bes of gold there are seven, or six, or five double sextulae of silver, then three parts of stibium are added to one part of gold; but in order that the stibium should not consume the gold, it is melted with copper in a red hot earthen crucible.[2-3]
Humans have been poking around in the dirt for millennia, and we've discovered quite a few minerals; but, have we discovered all of Earth's minerals? While it might seem that there should always be another mineral buried somewhere just waiting to be discovered, it's actually possible to estimate how many undiscovered minerals there may be. How could something like this be done?
As an example, let's look at the number of bird species. The following graph shows the progress in finding new species of birds as a function of time. To put these data into perspective, Charles Darwin's discovery of many new species of finches on the second voyage of the HMS Beagle happened in 1837. As an educated guess, we can conclude that nearly every bird species has been discovered.
The curve through the points in the above graph resembles a curve called the error function. This function, which is related to the normal distribution, is defined as follows:
As you can see, the error function is not that easy to compute. Fortunately, most spreadsheet programs will calculate values of the error function, typically by calling erf(), so that's not a problem. Spreadsheets and other application programs that use the error function compute it as a series expansion, as follows:
In this expansion, the denominators of the fractions are given by n!(2n + 1). We can see how well an error function fits the bird species data in the graph below. In this case, the fitted function is (1 + erf((Year-1845)/60))/2, and we see how knowledge of where we are on the curve tells us how many species are left to be discovered.
A team of mineralogists from the Carnegie Institution for Science (Washington, DC), the University of Arizona (Tucson, Arizona), and the University of Maine (Orono, Maine) took a different approach to finding the number of undiscovered minerals.[5-6] As explained by team leader, Robert Hazen from the Carnegie Institution, "Minerals follow the same kind of frequency of distribution as words in a book," so the number of rare minerals can be estimated based on the distribution of common minerals.
The probability that a mineral type exists at ten or fewer locations is about 65%, while that probability drops to 22% for minerals existing in just one place. Most mineral types are rare, being found in five or fewer places. The research team found that the Earth contains 4,831 known minerals, as sampled from 135,415 locations, and their analysis indicates that there are perhaps 1,563 minerals yet to be discovered.[5-6]
As mentioned earlier in this article, Earth's minerals reflect its oxidizing environment. That oxidizing environment was established by photosynthetic organisms during the Great Oxygenation Event about 2.3 billion years ago. About two-thirds of Earth's minerals would not exist if life did not evolve on Earth.[7-8] This finding indicates that the geology of exoplanets would be quite different from that of Earth.
- Urit me Glycerae nitor/Splendentis Pario marmore purius. (I burn when I see Glycera, purer than Parian marble) Quintus Horatius Flaccus, Ode XIX, from "The Odes of Horace," book 1, Engl. verse tr. by J.J. Lonsdale (Richard Bentley and Son, London, 1879), p. 50 (via Google Books).
- Herbert Clark Hoover and Lou Henry Hoover, translators, "De Re Metallica" by Georgius Agricola, Dover Publications, (New York, 1950), p. 452.
- Georg Agricola, "De re metallica," Hieron Frobenium et Nicolaum Episcopium, (Basil, 1556), in Latin, via the Internet Archive.
- Bird species discovery odds and ends, Slybird Blog, December 14, 2010.
- Robert M. Hazen, Grethe Hystad, Robert T. Downs, Joshua Golden, Alex J. Pires, and Edward S. Grew, "Earth's “missing” minerals," American Mineralogist (In Press, June, 2015).
- Earth's mineralogy unique in the cosmos , Carnegie Institution Press Release, August 26, 2015.
- Robert M. Hazen, Dominic Papineau, Wouter Bleeker, Robert T. Downs, John M. Ferry, Timothy J. McCoy, Dimitri A. Sverjensky, and Hexiong Yang, "Mineral evolution," American Mineralogist, vol. 93 (November-December, 2008), pp. 1693–1720.
- Roberta Kwok, "How Life and Luck Changed Earth's Minerals," Quanta Magazine, August 11, 2015.
Permanent Link to this article
Linked Keywords: Child; Children; rock; colleague; mineralogy; geology; Golden Books; sedimentary; igneous; metamorphic; conglomerate; marble; metamorphose; limestone; sculpture; sculpting; material; Roman poet; Horace; whiteness; Paros; Parian marble; Odes; statue; Jupiter; Capitoline Triad; Palestrina; Wikimedia Commons; mineral; crystal; crystallite; chemical compound; oxide; oxidize; environment; sulfide; sulphate; quartz; corundum; magnetite; hematite; calcite; gypsum; galena; pyrite; plagioclase; human; mining; mine; Earth; prehistory; prehistoric times; flint; weapon; hematite; pigment; smelting; smelt; metal; gold; silver; copper; jewelry; cookware; armor; extractive metallurgy; chemical extraction of metal; century; De Re Metallica; Georgius Agricola; antimony; incandescence; clay; crucible; mineralogy; dirt; millennium; millennia; bird; species; data; Charles Darwin; Darwin's finches; second voyage of the HMS Beagle; educated guess; bird; species; function; Gnumeric; error function; normal distribution; spreadsheet program; series expansion; denominator; fraction; Carnegie Institution for Science (Washington, DC); University of Arizona (Tucson, Arizona); University of Maine (Orono, Maine); Robert Hazen; fFrequency distribution">frequency of distribution; word; book; probability; research; hazenite; Mono Lake, California; Hexiong Yang; photosynthesis; photosynthetic; organism; Great Oxygenation Event; evolution; exoplanet.
Latest Books by Dev Gualtieri
Thanks to Cory Doctorow of BoingBoing for his favorable review of Secret Codes!
Blog Article Directory on a Single Page
- The Wisdom of Composite Crowds - April 27, 2017
- J. Robert Oppenheimer and Black Holes - April 24, 2017
- Modeling Leaf Mass - April 20, 2017
- Easter, Chicks and Eggs - April 13, 2017
- You, Robot - April 10, 2017
- Collisions - April 6, 2017
- Eugene Garfield (1925-2017) - April 3, 2017
- Old Fossils - March 30, 2017
- Levitation - March 27, 2017
- Soybean Graphene - March 23, 2017
- Income Inequality and Geometrical Frustration - March 20, 2017
- Wireless Power - March 16, 2017
- Trilobite Sex - March 13, 2017
- Freezing, Outside-In - March 9, 2017
- Ammonia Synthesis - March 6, 2017
- High Altitude Radiation - March 2, 2017
- C.N. Yang - February 27, 2017
- VOC Detection with Nanocrystals - February 23, 2017
- Molecular Fountains - February 20, 2017
- Jet Lag - February 16, 2017
- Highly Flexible Conductors - February 13, 2017
- Graphene Friction - February 9, 2017
- Dynamic Range - February 6, 2017
- Robert Boyle's To-Do List for Science - February 2, 2017
- Nanowire Ink - January 30, 2017
- Random Triangles - January 26, 2017
- Torricelli's law - January 23, 2017
- Magnetic Memory - January 19, 2017
- Graphene Putty - January 16, 2017
- Seahorse Genome - January 12, 2017
- Infinite c - January 9, 2017
- 150 Years of Transatlantic Telegraphy - January 5, 2017
- Cold Work on the Nanoscale - January 2, 2017
- Holidays 2016 - December 22, 2016
- Ballistics - December 19, 2016
- Salted Frogs - December 15, 2016
- Negative Thermal Expansion - December 12, 2016
- Verbal Cues and Stereotypes - December 8, 2016
- Capacitance Sensing - December 5, 2016
- Gallium Nitride Tribology - December 1, 2016
- Lunar Origin - November 27, 2016
- Pumpkin Propagation - November 24, 2016
- Math Anxiety - November 21, 2016
- Borophene - November 17, 2016
- Forced Innovation - November 14, 2016
- Combating Glare - November 10, 2016
- Solar Tilt and Planet Nine - November 7, 2016
- The Proton Size Problem - November 3, 2016
Deep Archive 2006-2008