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August 13, 2009
 
Playa Dust Chemistry 101

Within the next few weeks, countless hordes of my friends will be making the mass migration to the a place called the "Playa," the Spanish word for "beach," the Burning Man word for both "home" and "dust." Burning Man is a festival out in the Black Rock Desert of northwestern Nevada, where a temporary city is built for one week out of the year, including art and creative people from all over the world. See the website for more. Go to the event if you want to get a description.

This year, I will not be going, after getting burned out last year. I went in 2007 and 2008, but organizing temples both years left me with a sour taste in my mouth like playa that had been pissed "not clear" on it. However, many of my friends are going, and may want to know just what the chemical composition of playa dust is. The following was posted by a person on Tribe.net a couple years ago.

Chemical Composition of Playa Dust (oxide percentages by weight):

• Silicon dioxide (SiO2): 43.10%
• Aluminum oxide (Al2O3): 11.80%
• Calcium oxide (CaO): 4.51%
• Magnesium oxide (MgO): 3.46%
• Potassium oxide (K2O): 2.82%
• Sodium oxide (Na2O): 2.29%
• Titanium dioxide (TiO2): 0.49%
• Phosphorus pentoxide (P2O5): 0.19%
• Manganese(II) oxide (MnO): 0.08%
• Loss on ignition (LOI): 25.4%
• Total: 99.52%

• Barium (Ba): 763 ppm
• Strontium (Sr): 354 ppm
• Zirconium (Zr): 161 ppm
• Zinc (Zn): 148 ppm
• Vanadium (V): 143 ppm
• Rubidium (Rb): 121 ppm
• Chromium (Cr): 64 ppm
• Copper (Cu): 42 ppm
• Nickel (Ni): 37 ppm
• Yttrium (Y): 32 ppm
• Gallium (Ga): 20 ppm
• Cobalt (Co): 14 ppm
• Lead (Pb): 13 ppm
• Niobium (Nb): 10 ppm

• Quartz (SiO2) Mj
• Feldspars Mj
• Micas Mj
• Clay minerals
• Pyroxenes
• Amphiboles
• Non-silicates Mn

This was sourced from: http://www.foresight.org/Conferences/MNT05/Papers/Gillett1/ See section 6.1 Table 2, about 2/3 down the html page. I'm not sure what the mj or mn means after some of the "semiquantitative minerals."

A couple of forum threads about this can be found: here and also here.

My summary of the thread discussion was this:

• The playa is abrasive because of aluminosilicates.
• The playa is corrosive because of carbonates.
• The caustic carbonates dissolve greases, such as lipids in the skin.
• The minerals are highly abrasive, ones often included in sandpaper and machining tools.

Human results from dissolved lipids and abrasion:

• Playa foot
• Miracle wart removal
• Microderm abrasion for softer skin
• Degradation of hair (this is my own guess based on what I've read on Wikipedia about shampoo and conditioner)

Other interesting facts:

• Playa can be added to molten glass.
• Playa is good for cement mixing.
• Playa + vinegar = science fair project!
• Spraying a large quantity of micro-fine mist of vinegar into a sandstorm would either be really cool, really smelly, and/or dangerous?
• HCL, hydrochloric acid (aka Muriatic Acid), can be used in VERY diluted amounts as a less smelly alternative to vinegar, but do not use on skin! Look for cement and other industrial cleaning solutions for muriatic acid.

Notes for the newbie:

• Bring vinegar, lemon juice, or some other low-strength skin-safe acid.
• Definitely bring mask and goggles.
• Plan to never go barefoot, even if naked, unless you wash your feet off multiple times a day. Playafoot = BAD.
• Do not bring anything of value or sentimental, unless it will be protected from corrosion or washable with vinegar.
• If renting a vehicle, wash with vinegar or lemon juice, before returning.

In regards to power or flames:

• No, it's pretty unlikely that small amounts of playa dust can be used to make some kind of really cool battery or flammable effect.

Later in one of the threads, a geologist geeked out and provided this paragraph of info:

"The basin and range province was formed by a series of occurances of extensional tectonics in the region caused by rifts, which results in normal faulting, with a steep upthrust side, (the "ranges") and a sloping side (forming the "basins"). Because they are so abruptly thrust upwards (geologically abrupt at least), they begin to undergo rapid weathering almost immediately. This leads to eolian input of sedimentary rocks into the deep basins, forming flat valleys.

"This is similar to graben valleys, such as those found at the East African rift divergent plate boundary, but there is no actual rift, and it is a much broader area, rather than a single rift. There are several theories as to why this extension is occurring -- possibly due to the transform fault between the Pacific and North American plate, possibly due to an underlying hotspot, possibly due to a newly forming rift/continental plate boundary -- but it is still very actively being studied. Some scientists even believe that the province started out as a full mountain range due to the impact of the laramide orogeny, which later subsided and subsequently forced the rest of the existing rock to spread, thin and fracture.

"Whatever the reason is, this fault system resulted in the area's unique drainage system, in which melted snow from the mountains runs into the basins to form lakes every season. As the temperature increases, these lakes evaporate leaving mineral deposits known as evaporites and, in this particular form, playa. The combination of the sedimentary eolian input (wind blown sediments) and evaporite minerals give the playa its characteristic chemical and mineralogical composition.

"Some of the more major (though there are many) minerals found in the playa are halite (sodium chloride, an evaporite also known as rock salt), natron (a mix of sodium bicarbonate, or baking soda, and soda ash, used in ancient egypt in mummification), borax (an evaporite containing sodium and boron, which often alters to its pseudomorph tincalconite through dehydration), thenardite (aka sodium sulfate, one of few evaporites that isn't commonly white, which gives a lot of the playa a pinkish color and if found in pure form is also fluorescent), mirabilite (hydrated sodium sulfate, having a tannish color, aka Glauber Salt) and trona (a sodium carbonate, named from an archaic Arabic word for salt, "tron").

"Note all the sodium in these minerals. This is why playa dust is referred to as alkaline. Sodium is an alkali metal, as any periodic table will tell you. Its valence is 1+, and therefore readily bonds with OH- molecules, forming all those lovely minerals you see above. OH- is hydroxide, which is the foundation of any base (as in acids/bases). Hence, Since there is so much sodium, there is a ton of hydroxide, and when that mixes with water, like the sweat on your feet, or anything else, it forms bases, leading to playa feet, etc. Therefore we use things that are acidic like lemon juice and vinegar (do not use HCl) to counteract this alkalinity."