Meteor That Fell in Russia Brings Back Memories of Lorton's Own Meteor

A meteor which a professor described to the New York Times as "about the size of an SUV" that hit the Earth's atmosphere Friday morning in Russia's Chelyabinsk region likely brought back some memories of Lorton's own brush with meteor fame.

The meteor that struck Russia created a "shock wave" — blowing out windows and TV sets and injuring possibly more than 1,000, some news reports say. Lorton's meteor? Not that big.

The Lorton meteor

It was a Monday, Jan. 18, 2010, about 5:45 p.m. when a half-pound meteor rocketed its way (likely traveling at about 220 MPH, the Smithsonian estimated at the time, in a story in the Washington Post) through the roof and ceiling of a Lorton doctors' office, Marc Gallini and Frank Ciampi's  Williamsburg Family Practice. The meteor lodged into the cement below the office carpeting. The doctors were in the office.

The rock (Channel 9 described it as the size of a mango) created a sensation — first as news of its existence spread and again when a dispute broke out between the doctors and their landlord over ownership of the meteorite. 

The landlord dropped the claim and the Smithsonian paid the doctors $10,000 for the meteor, which they donated to charity. The meteorite now resides at the Smithsonian's Department of Mineral Sciences.

Here's a description of the meteorite that struck in Lorton, from the Smithsonian's Department of Mineral Sciences:

On Monday, January 18, 2010, a large fireball was reported by viewers in the greater Washington, DC, USA, metropolitan area. Reports from as far away as New Jersey describe a large greenish fireball moving roughly south and east between 5:30 and 5:45 PM. Reports from Virginia include sounds of a large detonation and smoke trails. Within minutes of the sightings, one stone was recovered from within the Williamsburg Square Family Practice in Lorton, VA. The doctors, who were in the office at the time of the fall, found the meteorite in three large pieces embedded into the carpet tile and concrete floor of an exam room. The doctors describe the sound of the impact as bookshelves crashing to the ground.

The meteorite is approximately 8 cm x 5 cm x 5 cm, and is roughly rectangular, with a matte black fusion crust. Fusion crust is a quenched glass, made from the meteorite itself, which forms from frictional heating during its atmospheric passage causing minute amounts of the rock to melt. The fireball is a combination of this same molten rock streaming off the heated surface and the superheated atmosphere surrounding it. Once the meteorite loses its cosmic velocity and slows to the point where the friction no longer heats the surface, the remaining melted rock freezes or "fuses" to the remaining stone, forming a glassy crust. For typical asteroidal materials, this "crust" is always thin (a few mm), smooth, without holes, and matte black.

The interior of the meteorite is light gray in color. To the naked eye, the Lorton meteorite contains thin dark veins, minute metal grains, a few small breccia clasts and even rarer relict chondrules. The meteorite was chemically analyzed in the Department of Mineral Sciences by Dr. Cari Corrigan and Linda Welzenbach. Classification of all ordinary chondrite meteorites is based primarily on the overall iron content derived from the composition of olivine and pyroxene. We also assign a number which corresponds to the degree of metamorphism experienced by the meteorite, the latter of which is merely a microscopic appraisal of chondrule preservation. Individual grains of olivine are reported as a range of fayalite compositional values, and pyroxene as ferrosilite values, both of which pertain to iron content. The lowest iron group is the LL chondrites, followed by L chondrites, with the highest iron group designated as the H chondrites.

The Lorton meteorite is classified as an L6 chondrite, which reflects low iron content, and a high metamorphic grade. The number 6 corresponds to the presence of rare chondrules, which when observed, show only diffuse boundaries or internal structure, and some degree of recrystallization, where crystals share boundaries that form 120-degree triple junctions. While chondrites make up nearly 90% of all meteorites classified, only a fraction are recovered as freshly fallen objects, and are highly valued because of the lack of terrestrial contamination and weathering. This meteorite fall is the first in the Washington DC area, and also the first in nearly 100 years—the closest are from Richmond, VA in 1828; St. Mary’s County, MD, in 1919; and Sharps, VA, in 1921. For now, the total mass recovered is 329.7 grams.

Why do we care about this meteorite? When we have a large number of one type of meteorite, we can compare and contrast the chemistry and textures within them to identify patterns and/or subtle differences that help us form a more complete picture. Another important thing about newly fallen meteorites is that we can examine the cosmogenic nuclides in them (short-lived elements that are generated by the sun) to learn more about a meteorite’s journey through the inner Solar System (between the asteroid belt and Earth). Each new fall has the potential to provide new clues to the earliest history and formation of the solar system.