MEZO-MADARAS

Stony

TIPO:

CLASSE:

CLAN:

GRUPO:

SUB-GRUPO:

TIPO PET.:

EST. CHOQUE:

INTERPERISMO:

PAÍS:

ANO:

DESCRIÇÃO:

CHONDRITE

ORDINARY

H-L-LL

L

-

3.7

S2

W0

ROMANIA

1852

Unequilibrated Ordinary Crondrite with polymitic breccias L 3.7. Shock Stage S2 and Weathering W0.

PETROGRAFIA:

Van Schmus (1967) called the main mass of Mezo-Madaras "normal", since he found three types of chondritic inclusions in the host material. Thus, there is a wide variety of chondrite in the main mass with the presence of porphyritic, radiant, barred and glassy textures. Olivine and pyroxene predominate in the chondrules. Pyroxene is typically a polysynthetically twin clinoenstatite with a low calcium content compared to clinohyperthene. Normal igneous zoning (Fe-poor centers and Mg-poor edges) is common in olivine and pyroxene crystals and, undoubtedly, represents the crystallization of these unequilibrated minerals during crystallization of the chondrules. The interstitial material of olivine and pyroxene in most chondrules consists of very fine-grained fibrous crystals, presumably olivine, pyroxene and plagioclase; this material probably represents the fibrous devitrification or crystallization of the residual melts that resulted in the chondrules during cooling and crystallization. Most of the metal and sulfide in this chondrite occurs outside the silicate cores as particles in the matrix or as droplets of metal sulfide. Metal and sulphide are generally mixed together. The Mezo-Madaras matrix includes fine-grained silicates (less than 10 microns in diameter), metal and sulfide. Source: Van Schmus (1967).

GEOQUÍMICA:

Olivine has an average composition of 15.7% Fe, Fa = 21.7 and PMD 28, which includes forsteritic cores, with some fayalitics edges. Pyroxene has an average of 7.5% Fe, Fs = 14.1 and PMD 44. Mezo-Madaras has a significant carbon content (0.46% by weight) and it is assumed that this carbon is predominantly in the matrix. Source: Van Schmus (1967)..

CLASSIFICAÇÃO:

Keil & Fredriksson (1964) determined that the compositions of olivine and pyroxene in the chondrite are extremely variable. Dodd and Van Schumus (1965) also noted that Mezo-Madaras contains primary glass in several of its tubes. This, in addition to the excellent preservation of the chondritic texture, led them to conclude that this meteorite experienced only a slight metamorphism. Dodd, Van Schmus and Marvin (1965, 1966) discovered a new mineral - merrihueite - in Mezo-Madaras, where it coexists with poor iron enstatite and fayalitic olivine. Wood (1967) studied the metal and sulfide phases and reported that the sulfide is nickel-free (trace amounts) and that FeNi was partitioned into kamacite and taenite, which led him to interpret this data as evidence of moderate metamorphism of low temperature (300-500ºC) in Mezo-Madaras. Based on general petrological properties and the lack of chemical equilibrium, Van Schmus & Wood (1967) placed Mezo-Madaras in their category of petrological type 3. Chemical analyses by Jarosewich (1967) and Ninns (1967) showed that this meteorite belongs to chondrites of L group. For more information on the meteorite, the link to the source article is https://www.sciencedirect.com/science/article/pii/001670376790141X. Source: Van Schmus (1967).

CLASSIFICADORES:

Not reported by the Meteorical Bulletin database. According to Van Schmus (1967), the first chemical analyzes of Mezo-Madaras were made by Rammelsberg (1871), while Meunier (1871) observed the polymeric nature of this meteorite. Other scientists have also contributed to the classification over the decades.

HISTÓRIA:

On April 9, 1852, at approximately 4:30 pm, a large fireball was witnessed following an SE-NE trajectory. The fireball was accompanied by thunder-type detonations and people near Lake Isten heard "humming noises" and witnessed the rocks falling from the sky. Source: www.historicmeteorites.com

Todas as informações que não possuírem fonte especifica, foram extraídas do Meteoritical Bulletin Database.

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