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Silistra
Basic information Name: Silistra
     This is an OFFICIAL meteorite name.
Abbreviation: There is no official abbreviation for this meteorite.
Observed fall: Yes
Year fell: 1917
Country: Bulgaria
Mass:help 0.15 g
Classification
  history:
Meteoritical Bulletin:  MB 100  (2012)  Achondrite-ung 
Recommended:  Achondrite-ung    [explanation]

This is 1 of 84 approved meteorites classified as Achondrite-ung.   [show all]
Search for other: Achondrites, Ungrouped achondrites
Comments: Approved 29 May 2012
Writeuphelp
Writeup from MB 100:

[NOTE: This provisional writeup was superseded 15 Sept 2017]

 

Silistra        44°7’N, 27°16’E

Silistra, Bulgaria

Fell: 19 July 1917

Classification: Ungrouped achondrite

History: A bolide was observed in the sky over Elena, Razgrad, and Silistra, Bulgaria, and Tulcea, Romania (fall direction SW - NE) at around 7 am on July 19, 1917. Several fragments were recovered but a single one reached the Mineralogy Museum of the University of Sofia (Dimov, 1975). Coordinates given are for Silistra town.

Physical characteristics: A single 0.15 g fragment (1.1 × 0.4 cm) was preserved; one side shows a smooth rounded fusion crust, the other a cut or broken inner surface. Porosity is estimated to be 86%.

Petrography: No crystals are observed on the SEM section. CT-scan and µXRF indicate very minor amount of dense crystals ~100 µm size.

Geochemistry: Oxygen isotopic composition lies on the HED fractionation line: (J. Gattacceca, C. Sonzogni, CEREGE). 

Classification: The material is composed almost entirely of vesicular glass, possibly related to eucrites.

Specimens: The main mass remaining after analysis is 0.125 g and resides at USof (curator E. Neykova). One polished micro-section and 10 mg are at CEREGE..


Writeup from MB 106:

Silistra        44°7’N, 27°16’E

Silistra, Bulgaria

Fell: 19 July 1917

Classification: Ungrouped achondrite

History: A bolide was observed in the sky over Elena, Razgrad, and Silistra, Bulgaria, and Tulcea, Romania (fall direction SW - NE) at around 7 am on July 19, 1917. Several fragments were recovered but a single one reached the Mineralogy Museum of the University of Sofia (Dimov, 1975). Coordinates given are for Silistra town.

Physical characteristics: A single 0.15 g fragment (1.1 × 0.4 cm) was preserved; one side shows a smooth rounded fusion crust, the other a cut or broken inner surface. Porosity is estimated to be 86%. The material is composed of vesicular glass and looks like a dark pumice. µCT-scan indicates homogeneous distribution of bubbles with moderate elongation. Bubbles diameter ranges from 10 μm to 3 mm, with median diameter of 70 μm. Based on fusion crust shape the full initial object can be estimated to be ~2 cc, 0.8 g object with a shape similar to core tektite.

Petrography: No crystals are observed on the SEM section. CT-scan and µXRF indicate very minor amount of dense crystals ~100 µm size identified as chromite and ilmenite based on Cr and Ti spots on the µXRF map.

Geochemistry: Oxygen isotopic composition was measured in CEREGE on two 1.5 mg powdered samples and lies on the HED fractionation line: δ17O = 2.64 and 2.50 ‰, δ18O = 5.55 and 5.30 ‰, and Δ17O = -0.27 and -0.27‰ per mil (J. Gattacceca, C. Sonzogni, CEREGE). HED falls were measured during the same session and fit with reference values. EMPA analysis (mean of 14 points) of the glass yield composition similar to cumulate eucrite: Fe/Mn= 29, Fe/Mg= 0.8 (atomic ratio); SiO2 48.6, FeO 15.2, Al2O3 14.2,CaO 9.9, MgO 9.2, MnO 0.5, Cr2O3 0.4, NaO 0.3, TiO2 0.1 (wt.%). K, Ni, S, Cl were undetectable. Average total at 98.2% suggest minor volatiles and Fe3+. Rare gas analyses (B. Marty, CRPG) indicate strong atmospheric contamination but significant content of cosmogenic 21Ne, pointing toward an apparent residence time in space of 0.2 Ma. Cosmogenic 3He is also present. Rare gas data indicate strong heating during atmospheric entry, but probably below the fusion temperature.

Classification: The material is composed almost entirely of vesicular glass, possibly related to eucrites based on oxygen isotopes and composition.

Specimens: The main mass remaining after analysis is 0.125 g and resides at USof (curator E. Neykova). One polished micro-section and 10 mg are at CEREGE.

Data from:
  MB100
  Table 1
  Line 1898:
State/Prov/County:Silistra
Origin or pseudonym:Silistra town
Date:19 July 1917
Latitude:44°7'N
Longitude:27°16'E
Mass (g):0.15
Pieces:1
Class:Achondrite-ung
Shock stage:Probable
Weathering grade:W0
Magnetic suscept.:2.56
Classifier:J. Gattacceca and P. Rochette, CEREGE
Type spec mass (g):0.125 g USof
Type spec location:USof
Main mass:USof
Comments:Submitted by P.Rochette, J. Gattacceca and V. Dekov
Plots: O isotopes:  
Institutions
   and collections
CEREGE: CEREGE BP 80 Avenue Philibert, Technopole de l'Arbois 13545 Aix-en-Provence Cedex 4 France, France (institutional address; updated 29 Oct 2018)
CRPG: Centre de Recherches Pétrographiques et Géochimiques, CNRS EP 2031, 15 rue Notre-Dame des Pauvres, BP 20, 54501 Vandoeuvre-lès-Nancy Cedex, France (institutional address; updated 27 Feb 2011)
USof: Museum of Mineralogy, Petrology and Ore Deposits; Department of Mineralogy, Petrology and Ore Deposits; University of Sofia; 15, Tzar Osvoboditel Blvd.; 1000 Sofia; Bulgaria, Bulgaria (institutional address; updated 21 May 2012)
Catalogs:
References: Published in Meteoritical Bulletin, no. 100, MAPS 49, E1-E101 (2014)
Published in Gattacceca J., Bouvier A., Grossman J., Metzler K., and Uehara M. (2019) Meteoritical Bulletin, no. 106. Meteorit. Planet. Sci. 54 in press.
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Geography:

Bulgaria
Coordinates:
     Recommended::   (44° 7'N, 27° 16'E)

Statistics:
     This is 1 of 2 approved meteorites from Razgrad, Bulgaria
     This is 1 of 6 approved meteorites from Bulgaria
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