Abstract
The meteorite with a single total mass of 630 gm as a visible meteorite has fallen on 22 March 2021, at 10:00 a.m. in Al-Sherqat subdistrict within Salah Al-Din, northern Iraq; and therefore, was named Al-Sherqat meteorite by the authors. It is characterized by a uniform structure of coherent and medium degree of malleability. It is of a well-crystalline structure and not homogeneous in composition. The Al-Sherqat meteorite is composed of metallic phases of 7.6 gm/cm3 density exhibiting an oriented intergrowth of kamacite (α-FeNi) with taenite showing a Widmanstätten pattern on an etched polished section with the finest octahedrite kamacite bandwidth of less than 0.2 mm. It is composed of Fe (86.9 wt%), Ni (9.63 wt%), P (1.31 wt%), S (0.628 wt%), Ti (0.623 wt%), Co (0.446 wt%), Mo (0.146 wt%), Cr (0.103 wt%), Cu (0.141 wt%), V (300 ppm), Nb (220 ppm), W (53 ppm), Ag (50 ppm), Pb (30 ppm), Zn (20 ppm), Sb (16 ppm), Sn (10 ppm) and As (3 ppm). Al-Sherqat meteorite was structurally classified as an iron meteorite belongs to the plessitic group (Opl)) with octahedrite finest bands (less than 0.2 mm) of the kamacite lamellae. Kamacite platelets in Al-Sherqat meteorite are almost not a continuous plate network. Chemically, it belongs to the IIC type of magmatic group based on the amount of nickel (9.63%), where IIC is typically octahedrites has 9.3 – 11.5% Ni. The presence of kamacite, taenite, schreibersite, daubréelites, pentlandite, chromite, and wusite in Al-Sherqat meteorite are in accordance with IIC group of the iron meteorites. Al-Sherqat meteorite belongs to M-type considering a metallic core fragmented by impact asteroid. The most probable source of this meteorite is the core of an asteroid that melted early in its history.
Highlights
Over the past centuries, and so far, only three main types of meteorites have been known: stony meteorites, iron-stony meteorites, and iron meteorites
Hexahedrites are entirely formed from kamacite and lack the Widmanstätten pattern, whereas, the octahedrite is composed of both kamacite and taenite (Wasson, 1969)
Kamacite is a pole of shaft broadly banded alloy, taenite is a ribbon characterized by a narrow alloy banded., whereas, plessite represents an alloy intermediate in properties between kamacite and taenite which fills in the angular interstices that occur between the intersecting bands
Summary
Only three main types of meteorites have been known: stony meteorites, iron-stony meteorites, and iron meteorites. The stony meteorites are composed mainly of silicates and called aerolites; the stony-iron meteorites are called siderolites composing of both metallic and silicates, forming from pallasites or mesosderites; and the iron meteorites, named siderites (Weisberg et al, 2006) are composed entirely of metals either nickel-poor kamacite or nickelrich taenite, which often occurs together (Howe and Knott,1962). The crystals of these two minerals are often interlocked and combined to form a characteristic feature named the Widmanstätten pattern which indicates the relatively low pressure at which iron meteorites are formed. The research aims mainly to document the fall of a new meteorite in the area of Al-Sherqat in northern Iraq, and to introduce a detailed description of the meteorite’s mineralogy, chemistry, and classification as well as the probable origin
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