This NWA 869 specimen’s surface shows signs of weathering. Mike Reynolds photo
Another installment of Michael Reynolds' series on meteorite:
This month I will focus on a stone meteorite that is readily available — even though we are seeing less and less of it and the prices are steadily increasing (more on meteorite pricing later!).
Morocco and the Sahara Desert are rich areas for meteorite recovery. Most such objects recovered in the Sahara Desert are stony meteorites; there have been a few iron and stony-iron meteorites found as well as some rare lunar and martian meteorites.
The most common meteorite recovered from the Sahara is Northwest Africa 869 (NWA 869). The naming convention for Saharan meteorites is not the typical scheme based on the closest post office box. These meteorites are found in the middle of the desert near no post office! So a numbering system used by the Meteoritical Society incorporates the order of recovery for specimens and their GPS locations. As of this blog, current Northwest Africa approved meteorites extend to NWA 5882, a discovery that yielded 44 grams of an ordinary chondrite meteorite recovered in 2009.
The NWA 869 strewn field, first found in 2000 and classified as an ordinary chondrite (L4-6), has produced around 2 tons of specimens. Whole meteorites, end pieces, and slices range from less than 1 gram in mass to greater than 20 kilograms.
The chemistry of the NWA 869 meteorite is interesting. It is a fragmented breccia that shows an internal matrix full of colors and chondrules when cut or sliced. Bits and flecks of meteoritic metal — iron and nickel — are usually easily visible. Meteoriticists may occasionally find carbonaceous inclusions in a specimen.
I remember the first time NWA 869 meteorites appeared at the Tucson Gem and Mineral Show. You could buy a kilogram of assorted meteorites for anywhere from a penny to a nickel per gram! Some meteorite collectors and dealers stocked up on NWA 869s, buying all they could find. The prices have gone up since that time. They range from 25 cents a gram upward. Cut and polished specimens cost more because of the work necessary to prepare them.
I am probably the only one on my block to have rock-cutting saws in my garage. I have a 7-inch water-lubricated wet saw and both 10-inch and 18-inch oil-lubricated cutters. These saws use water or cutting oil as the lubricant. NWA 869 meteorites cut fine with either type of saw. The blades are designed for meteorites and are expensive. The last blade I bought for my 10-inch saw cost $99. The life of the blade depends on what type of meteorite I cut. It lasts longer for stony meteorites than for iron meteorites. A dull blade not only makes cutting slow, but it also can cause the blade to bind or leave “burn marks” on a specimen as the blade and meteorite overheat.
After cutting an NWA 869, I use a whetstone to take out marks left by the saw. Then I use an oscillating sander to give the slice a nice finish. I have also used a cabbing machine to finish meteorite slices. A cabbing machine, long used by rock hounds in preparation of cabochons and other finished slices, is basically a grinder with one or more wheels to smooth a whole stone or a slice. Increasingly finer grit wheels allow me to create a smooth and polished specimen.
Mike Reynolds cuts an NWA 869 meteorite on a wet saw. Courtesy Mike Reynolds
I like NWA 869 meteorites for several reasons. First, you can buy a large specimen and not pay a lot of money compared to other meteorites. Second, you can buy a lot of smaller NWA 869 specimens for a classroom exercise or as outreach. I love giving kids pieces of NWA 869 as well as Campo del Cielo, an iron meteorite. Another reason I like NWA 869 meteorites is that when you slice and polish a specimen, the interior matrix is simply beautiful. NWA 869 is a good example of an ordinary chondrite, and the internal matrix never fails to please collectors.
Some note that NWA 869 meteorites don’t look much like a meteorite or even anything impressive. I would agree except it is from space! It is true NWA 869 specimens do not have the dense feeling of an iron meteorite such as Canyon Diablo, the unusual markings of Sikhote-Alin, or the beauty of the internal matrix of Imilac, a wonderful stony-iron pallasite.
When buying an NWA 869, a collector might get a Northwest African meteorite that is not a true NWA 869. Some meteorite dealers sell unidentified Northwest African meteorites as NWA Unknowns. Some even improperly label NWA Unknowns as NWA 869. The characteristics of NWA 869 are different enough from these NWA Unknown meteorites that most dealers, experienced collectors, and researchers can tell them apart.
NWA Unknown meteorites should be selling for a lot less than any properly named meteorite. The one advantage of buying NWA Unknown meteorites is that you might get a rare meteorite for a low per-gram price. I know several collectors who have found their NWA Unknowns to be achondrites or even lunar or martian meteorites!
This NWA Unknown’s shape shows extreme weathering and looks like sandstone.
This NWA Unknown’s shape shows extreme weathering and looks like sandstone. Mike Reynolds photo
I recommend buying Northwest Africa 869 meteorites while you can still get them. Some countries are restricting meteorite exports. The penalties can be severe. For now, however, you can purchase a nice NWA 869 whole, end-cut piece, or slice for a good price. It’s an easy way to get yourself a nice stone meteorite.
Do you have a meteorite or cratering question? How and where to buy meteorites? Collecting tales? Successful meteorite hunts? A favorite meteorite? Favorite meteorite books and publications? A must-see meteorite exhibit? Please e-mail me at
mreynold@fscj.edu. We will explore your meteorite questions and more each month!
Related: Meteorite expert Mike Reynolds chats about falling stars