Finds from Dense Collection Area (DCA) Strewn Fields
When a meteorite is found in a Dense Collection Area (DCA) and then classified, oftentimes some or much more of the same material is found. In some cases, this new material goes through its own classification process to become “officially paired”, but more often it is sold by brokers to dealers and collectors who then decide which path they will take.
Note that the guidelines below regarding unofficial pairings do not adhere to the Meteoritical Society guidelines required for scientific research and publications. As the Meteoritical Society and GMA have differing goals and missions, the guidelines below are meant to provide sufficient clarity for a buyer to make an educated purchasing decision. Furthermore, the definitions below are guidelines and unlikely to cover all circumstances.
Members may never use someone else’s dense collection area (DCA) name published in the MetBull without first either getting written permission from published mass holder(s), or adding a modifier to the description making it clear that this specimen is an unofficial pairing. Meteorites from Dense Collection Areas are easily identified as their name will include a general name for the area followed by a number. DCA meteorites require additional scrutiny as exact recovery locations are rarely provided or unavailable to the person classifying the meteorite.
Note: In text below, substitute the words “published meteorite” with the actual name of the meteorite as identified in the MetBull: e.g. NWA 011, DHO 1988
Pairings of DCA (e.g., NWA, DHO, Stewart Valley) meteorites include:
- Unofficial: “Visually Paired to”, “Source Paired to” or “Likely Paired to” published meteorite.
- Sellers must state that the specimen is “Visually Paired to” or “Source Paired to” published meteorite in the title of a listing or offer to sell/trade, and in any description related to classification. This information must be easily accessible to prospective buyers for them to make an educated purchasing decision.
- Visually Paired definition: A meteorite that can be paired to another DCA meteorite due to some unique feature(s) readily distinguished by the naked eye.
- Source Paired definition: A meteorite that can be paired to another DCA meteorite based on the source of their purchase:
- The same dealer or broker who sold the unclassified stone to the original person who had the meteorite classified.
- The meteorite was purchased from a different dealer or broker, but the material came from the same strewn field.
- Likely Paired definition: A meteorite that, based on the judgment of the seller, can be paired to another DCA meteorite. Likely paired meteorites often combine source and visually paired characteristics.
- In all these cases, buyers are encouraged to ask seller as much information as possible from the seller to make an educated decision.
- Unofficial: “Lab Paired to” or “Scientifically Paired to” published meteorite
- Sellers must state that the specimen is “Lab Paired to” or “Scientifically Paired to” published meteorite in the title of a listing or offer to sell/trade, and in any description related to classification. This information must be easily accessible to prospective buyers for them to make an educated purchasing decision.
- Either term is acceptable and provides an extra level of confidence to a prospective buyer. The definition of such a term means that a specimen has been provided to a recognized meteoritical scientist or institution and that they have performed sufficient analysis to confirm that the specimen in question is paired. In such a case, the scientist or institution should be disclosed to the seller prior to the finalizing the sale. Sellers are encouraged to have the specimen analyzed by the same institution or scientist that performed the original classification.
- Official: Paired to published meteorite
- Describes any DCA meteorite that has gone through the entire classification process including deposit of required type specimen, been assigned its own DCA number, may list names of previously approved paired meteorites in the description, been approved by the NomCom, and been officially published in the MetBull.
Named Falls and Named Finds from Non-DCA Strew Fields
Per the Meteoritical Society, meteorites recovered from a fall or collected from a non-DCA strewn field with known coordinates/location may be self-paired by the finder. There is no concept of “pairings” for meteorites recovered from recognized strewn fields. For example, meteorites recovered today from the Chelyabinsk strewn field are also considered Chelyabinsk meteorites even if their mass is not included in the total known weight listed in the Meteoritical Bulletin.