Bolides & Impact-Craters, & their Debris (Meteorites & Tektites) Continued... By Wayne Farley

Nevertheless, the author’s recent study of five moldavite sets (bracelet, brooch, and earrings) from the second half of the 19th century in the collection of the Museum of Decorative Arts in Prague revealed an unexpected result. Only one set contained moldavites—a donation to the museum by Olga Havlova, the first wife of Vaclav Havel, the late Czech author and statesman. All of the stones in the other four sets proved to be glass imitations. This means that glass imitations have been around decades longer than previously thought (figure 1). Fortunately, the identification of faceted moldavite is simple. Besides their flow texture and abundant bubbles (almost always much more abundant than in an artificial glass), moldavites contain “wires” of lechatelierite, a high-temperature form of SiO2. Lechatelierite is very easy to see with a loupe due to its lower RI.” (GIA, Ref-8) 


Best Private Meteorite Collection (Ref-7): Naveen Jain isn’t your average rock collector. His home office in Bellevue, Washington, is a showcase for more than 500 specimens, all of them drop-shipped to Earth from outer space. It’s one of the world’s most complete meteorite collections. “I have at least one of every type of specimen,” says the 52-year-old founder of the search engine InfoSpace, digital security firm Intelus, and Moon Express, and a company that aims to land a robotic craft on the lunar surface next year. Jain, who as CEO of InfoSpace rode the dotcom rocket onto Forbes’ list of wealthiest Americans, has spent $5 million to date. He collects only meteorites that someone has seen streaking through the atmosphere, known as witnessed falls. They’re unweathered and uncontaminated by terrestrial detritus, and museums and collectors snap them up nearly as fast as they fall to Earth. Take the Martian brick that fell on Chassigny, France, on October 3, 1815: With only 750 grams extant, fragments can  cost $100,000 per gram, or 2,000 times the price of gold. (Jain has a 4-gram piece.)


Hoba, the Largest Meteorite on Earth: The Hoba meteorite (Fig-5) is the largest known meteorite on Earth, it’s also the single largest piece of naturally occurring iron weighing in at around 60 tons. In terms of actual size it measures 2.7 metres by 2.7 metres (8 feet 9 inches) by 0.9 metres (3 feet). It’s believed to have touched down some 80,000 years ago in modern day Namibia and was only discovered in 1920 after the owner of the land ran over it with his plow. Chemically the meteorite is composed of about 84% iron and 16% nickel.  


The Biggest meteorite found in the U.S. (Fig-6) was found in West Linn, Oregon, in 1902. It is called the Willamette Meteorite.  The massive 16-ton chunk of iron was found by a neighbor property owner, who dragged it half a mile to his own property in an attempt to steal it. Today it's in the New York Museum of Natural History.


Most Unique Iron Meteorite in the World: The Tucson Ring meteorite (Fig-7) is the most well known iron meteorite in the world primarily because of its exotic shape but also because of its storied history. It was first reported by Jose Velasco of Sonora, Mexico in 1845 from his treatise on mining in the region. He described a mountain pass, Puerta de los Muchacos (today known as Box Canyon), in the Sierra de la Madera range (Santa Rita Mountains today) where large masses of pure iron were found at the base of the mountains. He described how one of the medium-sized masses was taken to Tucson, 30 hard miles away, where it was used as an anvil for the garrison blacksmith. Somehow a second large mass was taken to the garrison between 1845 and 1850 again to be used as an anvil, and this meteorite became known as "The Carleton". Pieces of the Ring were analyzed in 1852 and determined to be of meteoritic origin. In 1856, The Ring was retired from service as an anvil and moved. In 1860, a medical officer Bernard Irwin located the abandoned Ring and took possession of it for the Smithsonian Institution. The Carleton went west to California for display until 1939 when it was purchased by the Smithsonian and reunited with the Ring in Washington. 


The Tucson Ring is unusual in that its mineralogy indicates that it was formed during a cataclysmic event whereby a small planet or asteroid was blasted apart by gravitational shear or impact with another body. As the body broke apart, the molten material ejected into space cooled and formed meteoroids and possibly smaller asteroids. The Tucson Ring cooled very quickly, indicating that it was part of a smaller remnant mass from the core or mantle of the destroyed planetoid. This is proven by the fact that the nickel-iron did not have time to crystallize and form the distinctive Widmanstatten figures that characterize and identify most iron meteorites. The Tucson Ring will not show Widmanstatten figures when etched because it was quenched quickly after the cataclysm. The Ring also has inclusions of clear glasses, further proving that it was quickly cooled. The Tucson Ring is the most highly sought-after iron meteorite in the world because only a small piece was removed from a knob on the inside margin of the Ring for analysis by the Smithsonian and no more will ever be removed. This means that the supply of this meteorite amounts to only a few hundred grams available to all of the scientific institutions and collectors worldwide. The chart that follows (Fig-8) shows the documented meteorites that have fallen in Montana, with the year of discovery, class, and the mass of the meteorite.


   Name             Year           Class           Mass 

    Beaverhead     ~600 mya  Impact Crater Dia.=100Km
Choteau    2011   Pallasite, ungrouped   8.47 kg     Harlowton   1975   Iron, IAB-ung   4 kg     

Illinois Gulch   1899   Iron, ungrouped   2.5 kg     Livingston   1936   Iron,IIIAB   1600 g     Lombard   1953   Iron, IIAB   7 kg     

      Roundup   1990   Iron, IIIAB   17.59 kg  

Twodot      1999         H6           21.4 kg 


A full slice of the Twodot stony meteorite, the only stony ever found in Montana, was purchased on eBay in 2012 by the Montana Council of Rock Clubs, and donated to the MT Tech Museum in Butte in 2013. The museum also has on exhibit ten other meteorites that "fell" into their collection over the years, including a large Ni-Fe meteorite found recently in Beaverhead County.  Another meteorite found near Victor, MT, reported to me in 2013, is still in private hands with a Victor collector.


Extinctions of Life from Bolide Impacts: The Permian–Triassic (P–Tr or P–T) extinction event, colloquially known as the Great Dying,[2] the End-Permian Extinction or the Great Permian Extinction,[3][4] occurred about 252 Ma (million years) ago,[5] forming the boundary between the Permian and Triassic geologic periods, as well as the Paleozoic and Mesozoic eras. It is the Earth's most severe known extinction event, with up to 96% of all marine species[6][7] and 70% of terrestrial vertebrate species becoming extinct.[8] It is the only known mass extinction of insects.[9][10] Some 57% of all families and 83% of all genera became extinct. Because so much biodiversity was lost, the recovery of life on Earth took significantly longer than after any other extinction event,[6] possibly up to 10 million years.[11] Studies in Bear Lake County near Paris, Idaho showed a quick and dynamic rebound in a marine ecosystem, illustrating the remarkable resilience of life.[12] There is evidence for one to three distinct pulses, or phases, of extinction.[8][13][14][15] Suggested mechanisms for the latter include one or more large meteor impact events, massive volcanism such as that of the  Siberian Traps, and the ensuing coal or gas fires and explosions,[16] and a runaway greenhouse effect triggered by sudden release of methane from the sea floor due to methane clathrate dissociation according to the clathrate gun hypothesis or methane-producing microbes known as methanogens.[17] Possible contributing gradual changes include sea-level change, increasing anoxia, increasing aridity, and a shift in ocean circulation driven by climate change. (Wikipedia) 


Other great extinctions (Fig-9) from bolides are listed in the chart below, with million years before present (MYBP) and percent of species extinction.
 

References: 

Wikipedia, 02/23/18  https://en.wikipedia.org/wiki/Bolide https://en.wikipedia.org/wiki/Tektite#Origins https://en.wikipedia.org/wiki/Beaverhead_crater https://en.wikipedia.org/wiki/Permian%E2%80%93Triassic_extinction_event National Geographic, 02/23/18  https://news.nationalgeographic.com/news/2013/13/130214-biggest-asteroid-impacts-meteorites-space-2012da14/ 

Reimold, W. U., and Gibson, R. L., “Meteorite Impact!, The Danger from Space and South Africa’s Mega-Impact, The Vredefort structure” 2009 Verma, Surendra: “The Tunguska Fireball”, 2005 Frank, Dr. Louis A. and Patrick Huyghe: “The Big Splash”, 1990 Povenmire, Hal: “Tektites A Cosmic Puzzle”, 2014 Wired, $5 million Meteorite Collection https://www.wired.com/2012/09/meteorite-collector/ GIA: “Gemological Institute of America”, Moldavite, Spring 2015 Frazier, Ann:”Mysterious Moldavite”, Lapidary Journal, August, 1991