When people think they have found a meteoriteWork in progress. A solid natural object reaching a planet’s surface from interplanetary space. Solid portion of a meteoroid that survives its fall to Earth, or some other body. Meteorites are classified as stony meteorites, iron meteorites, and stony-iron meteorites. These groups are further divided according to their mineralogy and Click on Term to Read More, much more often than not, what they found is actually a terrestrial rock, often referred to as a meteorwrong. These rocks come in all shapes, sizes, colors and textures, and sometimes include holes. In posting these specimens for review, they may be told that “meteorites do not have holes”. Though generally true, this statement misleading because a simple internet search will uncover images of actual meteorites with holes. This article is written to clarify this issue.
Though our definitions for holes and cavities differ somewhat from the dictionary definition, they are better descriptors than what is normally used to describe meteorites.
Holes can be caused by ablationGradual removal of the successive surface layers of a material through various processes. • The gradual removal and loss of meteoritic material by heating and vaporization as the meteoroid experiences frictional melting during its passage through the atmosphere. The resulting plasma ablates the meteor and, in cases where a meteor Click on Term to Read More or various types of terrestrial weathering and generally describe a voidHuge region of space that is unusually empty of galaxies. Voids are not entirely empty, but are underdense and contain far fewer bright galaxies than average. that extends all the way through a specimen.
Cavities can also be caused by ablation and in that case are called regmaglypts, or by the weathering of softer or more degradable material within the meteorites such as troiliteBrass colored non-magnetic Fe sulfide, FeS, found in a variety of meteorites. in iron meteorites.
Vesicles are caused due due trapped gases expanding within the molten material/melt at its time of formation and are rarely bigger than a few millimeters, though in extremely rare cases one or two larger vesicles can by be larger. Vesicles inside meteorites do not occur due to its voyage through our atmosphere, though bubbles/vesicles can form on the outside crustOutermost layer of a differentiated planet, asteroid or moon, usually consisting of silicate rock and extending no more than 10s of km from the surface. The term is also applied to icy bodies, in which case it is composed of ices, frozen gases, and accumulated meteoritic material. On Earth, the Click on Term to Read More during entry.
My recommendation is you start up a catalog now keep track of important info on your collection when you bought it total weight total cost, details of why it interested you etc. if you keep at it it’s hard to “catch up” on details later. The little nuances you might forget in a piece in 3 decades or 400 pieces later
Please categorize any and all new specimens collections – keep records, I am truly sorry I didn’t when I was purchasing prior 10-12 years ago. Now I just have a mess of things I am now trying to rectify
The Meteoritical Bulletin is filled with incredible meteorite-related information. However, even the most experienced collector might be puzzled when evaluating a classification and trying to understand the various punctuation used by the Nomenclature Committee. For example, do you understand the difference between an L/LL3 and an L(LL3)? Please note that the punctuation only covers chondritesChondrites are the most common meteorites accounting for ~84% of falls. Chondrites are comprised mostly of Fe- and Mg-bearing silicate minerals (found in both chondrules and fine grained matrix), reduced Fe/Ni metal (found in various states like large blebs, small grains and/or even chondrule rims), and various refractory inclusions (such Click on Term to Read More. There is little carryover into the achondrites, irons and stony-irons, and within these other groups, there are discrepancies.
Meaning Behind Punctuation in Chondrite Classifications:
G = chondriteChondrites are the most common meteorites accounting for ~84% of falls. Chondrites are comprised mostly of Fe- and Mg-bearing silicate minerals (found in both chondrules and fine grained matrix), reduced Fe/Ni metal (found in various states like large blebs, small grains and/or even chondrule rims), and various refractory inclusions (such Click on Term to Read More group (H, L, LL, CM, CK, R, …)
Gx = first chondrite group
Gy = second chondrite group
Ta = first chondrite petrologic typeMeasure of the degree of aqueous alteration (Types 1 and 2) and thermal metamorphism (Types 3-6) experienced by a chondritic meteorite. Type 3 chondrites are further subdivided into 3.0 through 3.9 subtypes.
Tb = second chondrite petrologic type
Gx(Gy) means a chondrite either of Group X or less likely Group Y. Example: L(LL3)
Gx/Gy means a chondrite of either Group X or Group Y. Example: L/LL3
One exception is Isheyevo, CH/CBb, where the slash means a chondrite that is transitional between the CH group and the CB group.
GxTa-Tb means a chondrite comprised of a brecciaWork in Progress ... A rock that is a mechanical mixture of different minerals and/or rock fragments (clasts). A breccia may also be distinguished by the origin of its clasts: (monomict breccia: monogenetic or monolithologic, and polymict breccia: polygenetic or polylithologic). The proportions of these fragments within the unbrecciated material Click on Term to Read More whose clasts/components range from petrologic Type A to Type B. Example: CK3-6
If A and B are one level apart, then means a chondrite of Type A and Type B. Example: R3-4
If the dash comes at the end of the group or type, then what follows provides added information. Examples: -melt breccia, -an, -ung
Used to denote a chondrite’s petrological subtype and only associated with Type 3 (unequilibrated), Type 2 and presumably Type 1. Example: CO3.0
These examples go beyond your standard meteorwrongs because they were created for fraudulent reasons. In fact some of these fakes, like Shirokovsky, can even sell as known fakes for more than some real pallasites!
Here is one of the most recent fakes that was submitted to Dr. Carl Agee for classification in summer of 2020.
Shirokovsky is categorized in the MetBull as a “pseudometeorite“. The write-up is somewhat ambiguous, and should not be. This meteorwrong was man-made with the intent to defraud collectors and institutions. It was sold originally as a fallMeteorite seen to fall. Such meteorites are usually collected soon after falling and are not affected by terrestrial weathering (Weathering = 0). Beginning in 2014 (date needs confirmation), the NomComm adopted the use of the terms "probable fall" and "confirmed fall" to provide better insight into the meteorite's history. If Click on Term to Read More from Feb. 1, 1956 and many well respected dealers were taken in. What is impressive is that the fraud persisted for a long time before it was properly identified. Now, these are collected as one of the best examples of a fake meteoriteWork in progress. A solid natural object reaching a planet’s surface from interplanetary space. Solid portion of a meteoroid that survives its fall to Earth, or some other body. Meteorites are classified as stony meteorites, iron meteorites, and stony-iron meteorites. These groups are further divided according to their mineralogy and Click on Term to Read More.