Ordinary chondrite, unequilibrated (LL3.3)
Fall, 20 June 1919; 24.3 g

A bright fireball, accompanied by lingering smoke, and thunderous detonations appeared in the afternoon, and at least one stone was seen to fall. A single stone of perhaps 500 g was recovered and kept as a family curio, but only 24 g was preserved. A larger portion of the meteorite may have fallen into Chesapeake Bay. The small piece preserved is, however, of great interest as it is one of the few witnessed falls of an unequilibrated LL chondrite (very low total iron) to be recovered. Olivine compositions are particularly variable (Fa0.2-77, ave Fa14). Variable pyroxenes are mostly clinopyroxenes. Much of the plagioclase has been converted to glass, but both anorthitic and albitic grains are found. Sulfides include both troilite and pentlandite. A number of additional minor phases have also been identified. A spinel-rich inclusion is mentioned as well.

Witnessed falls of 14 unequilibrated LL chondrites are listed at the Meteoritical Society's 'Meteoritical Bulletin Database' (as of August 2015). However, only 4 of those are listed as even more primitive (less metamorphosed) than St. Mary's County. Two of the even more primitive falls are the Semarkona (LL3.0) and the Bishunpur (LL3.15) meteorites.

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Standard Detailed Gallery Strunz Chemical Elements

Mineral List

10 valid minerals.

Meteorite/Rock Types Recorded

Note: data is currently VERY limited. Please bear with us while we work towards adding this information!

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Alphabetical List Tree Diagram

ⓘ 'LL3.3 chondrite meteorite'

Detailed Mineral List:

ⓘ Albite

Formula: Na(AlSi₃O₈)

Description: In mesostasis.

Reference: Grossman, J. N. & Brearley, A. J. (2003). Cryptic metamorphic effects in chondrules from highly unequilibrated ordinary chondrites: An insidious parent-body process. Lunar and Planetary Science Conference XXXIV, pdf#1584.

ⓘ Chromite

Formula: Fe²⁺Cr³⁺₂O₄

Reference: Noonan, A. F., Jarosewich, E., & Clarke, R. S., Jr. (1977) The St. Mary's County, Maryland, Chondrite: Smithsonian Contributions to Earth Science 19,96-103.

ⓘ Clinoenstatite

Formula: MgSiO₃

Reference: Noonan, A. F., Jarosewich, E., & Clarke, R. S., Jr. (1977) The St. Mary's County, Maryland, Chondrite: Smithsonian Contributions to Earth Science 19,96-103.

ⓘ 'Clinopyroxene Subgroup'

Reference: Noonan, A. F., Jarosewich, E., & Clarke, R. S., Jr. (1977) The St. Mary's County, Maryland, Chondrite: Smithsonian Contributions to Earth Science 19,96-103.

ⓘ Copper

Formula: Cu

Reference: Noonan, A. F., Jarosewich, E., & Clarke, R. S., Jr. (1977) The St. Mary's County, Maryland, Chondrite: Smithsonian Contributions to Earth Science 19,96-103.

ⓘ 'Fayalite-Forsterite Series'

ⓘ Forsterite

Formula: Mg₂SiO₄

Reference: Noonan, A. F., Jarosewich, E., & Clarke, R. S., Jr. (1977) The St. Mary's County, Maryland, Chondrite: Smithsonian Contributions to Earth Science 19,96-103.

ⓘ 'Glass'

Reference: Noonan, A. F., Jarosewich, E., & Clarke, R. S., Jr. (1973) The St. Mary's County, Maryland, LL3 chondrite. Meteoritics 8:61 - 62.; Grossman, J. N. & Brearley, A. J. (2003). Cryptic metamorphic effects in chondrules from highly unequilibrated ordinary chondrites: An insidious parent-body process. Lunar and Planetary Science Conference XXXIV, pdf#1584.

ⓘ Iron

Formula: Fe

ⓘ Iron var. Kamacite

Formula: (Fe,Ni)

ⓘ Pentlandite

Formula: (Ni_xFe_y)_Σ9S₈

ⓘ 'Plagioclase'

Formula: (Na,Ca)[(Si,Al)AlSi₂]O₈

Reference: Noonan, A. F., Jarosewich, E., & Clarke, R. S., Jr. (1977) The St. Mary's County, Maryland, Chondrite: Smithsonian Contributions to Earth Science 19,96-103.

ⓘ 'Pyroxene Group'

Formula: ADSi₂O₆

Reference: Noonan, A. F., Jarosewich, E., & Clarke, R. S., Jr. (1973) The St. Mary's County, Maryland, LL3 chondrite. Meteoritics 8:61 - 62.

ⓘ Spinel

Formula: MgAl₂O₄

ⓘ Taenite

Formula: (Fe,Ni)

Reference: Noonan, A. F., Jarosewich, E., & Clarke, R. S., Jr. (1977) The St. Mary's County, Maryland, Chondrite: Smithsonian Contributions to Earth Science 19,96-103.

ⓘ Troilite

Formula: FeS

Reference: Noonan, A. F., Jarosewich, E., & Clarke, R. S., Jr. (1973) The St. Mary's County, Maryland, LL3 chondrite. Meteoritics 8:61 - 62.; Noonan, A. F., Jarosewich, E., & Clarke, R. S., Jr. (1977) The St. Mary's County, Maryland, Chondrite: Smithsonian Contributions to Earth Science 19,96-103.; Grady, M.M. (2000). Catalogue of Meteorites (5/e). Cambridge University Press: Cambridge; New York; Oakleigh; Madrid; Cape Town. 689 pages.

Gallery:

List of minerals arranged by Strunz 10th Edition classification

Group 1 - Elements
ⓘ	Copper	1.AA.05	Cu
ⓘ	Iron	1.AE.05	Fe
ⓘ	var. Kamacite	1.AE.05	(Fe,Ni)
ⓘ	Taenite	1.AE.10	(Fe,Ni)
Group 2 - Sulphides and Sulfosalts
ⓘ	Pentlandite	2.BB.15	(Ni_xFe_y)_Σ9S₈
ⓘ	Troilite	2.CC.10	FeS
Group 4 - Oxides and Hydroxides
ⓘ	Chromite	4.BB.05	Fe²⁺Cr³⁺₂O₄
ⓘ	Spinel	4.BB.05	MgAl₂O₄
Group 9 - Silicates
ⓘ	Albite	9.FA.35	Na(AlSi₃O₈)
ⓘ	Clinoenstatite	9.DA.10	MgSiO₃
ⓘ	Forsterite	9.AC.05	Mg₂SiO₄
Unclassified Minerals, Rocks, etc.
ⓘ	'Clinopyroxene Subgroup'	-
ⓘ	'Fayalite-Forsterite Series'	-
ⓘ	'Glass'	-
ⓘ	'Plagioclase'	-	(Na,Ca)[(Si,Al)AlSi₂]O₈
ⓘ	'Pyroxene Group'	-	ADSi₂O₆

List of minerals for each chemical element

O	Oxygen
O	ⓘ Pyroxene Group	ADSi₂O₆
O	ⓘ Spinel	MgAl₂O₄
O	ⓘ Chromite	Fe²⁺Cr₂³⁺O₄
O	ⓘ Clinoenstatite	MgSiO₃
O	ⓘ Forsterite	Mg₂SiO₄
O	ⓘ Plagioclase	(Na,Ca)[(Si,Al)AlSi₂]O₈
O	ⓘ Albite	Na(AlSi₃O₈)
Na	Sodium
Na	ⓘ Plagioclase	(Na,Ca)[(Si,Al)AlSi₂]O₈
Na	ⓘ Albite	Na(AlSi₃O₈)
Mg	Magnesium
Mg	ⓘ Spinel	MgAl₂O₄
Mg	ⓘ Clinoenstatite	MgSiO₃
Mg	ⓘ Forsterite	Mg₂SiO₄
Al	Aluminium
Al	ⓘ Spinel	MgAl₂O₄
Al	ⓘ Plagioclase	(Na,Ca)[(Si,Al)AlSi₂]O₈
Al	ⓘ Albite	Na(AlSi₃O₈)
Si	Silicon
Si	ⓘ Pyroxene Group	ADSi₂O₆
Si	ⓘ Clinoenstatite	MgSiO₃
Si	ⓘ Forsterite	Mg₂SiO₄
Si	ⓘ Plagioclase	(Na,Ca)[(Si,Al)AlSi₂]O₈
Si	ⓘ Albite	Na(AlSi₃O₈)
S	Sulfur
S	ⓘ Pentlandite	(Ni_xFe_y)_Σ9S₈
S	ⓘ Troilite	FeS
Ca	Calcium
Ca	ⓘ Plagioclase	(Na,Ca)[(Si,Al)AlSi₂]O₈
Cr	Chromium
Cr	ⓘ Chromite	Fe²⁺Cr₂³⁺O₄
Fe	Iron
Fe	ⓘ Iron var. Kamacite	(Fe,Ni)
Fe	ⓘ Pentlandite	(Ni_xFe_y)_Σ9S₈
Fe	ⓘ Troilite	FeS
Fe	ⓘ Chromite	Fe²⁺Cr₂³⁺O₄
Fe	ⓘ Taenite	(Fe,Ni)
Fe	ⓘ Iron	Fe
Ni	Nickel
Ni	ⓘ Iron var. Kamacite	(Fe,Ni)
Ni	ⓘ Pentlandite	(Ni_xFe_y)_Σ9S₈
Ni	ⓘ Taenite	(Fe,Ni)
Cu	Copper
Cu	ⓘ Copper	Cu

References

Sort by

Year (asc) Year (desc) Author (A-Z) Author (Z-A)

Noonan, A. F., Jarosewich, E., & Clarke, R. S., Jr. (1973) The St. Mary's County, Maryland, LL3 chondrite. Meteoritics 8:61 - 62.

Noonan, A. F., Jarosewich, E., & Clarke, R. S., Jr. (1977) The St. Mary's County, Maryland, Chondrite: Smithsonian Contributions to Earth Science 19,96-103.

Grady, M.M. (2000). Catalogue of Meteorites (5/e). Cambridge University Press: Cambridge; New York; Oakleigh; Madrid; Cape Town. 689 pages.

Grossman, J. N. & Brearley, A. J. (2003). Cryptic metamorphic effects in chondrules from highly unequilibrated ordinary chondrites: An insidious parent-body process. Lunar and Planetary Science Conference XXXIV, pdf#1584.

Grady, M.M., Pratesi, G. & Moggi-Cecchi, V. (2015) Atlas of Meteorites. Cambridge University Press: Cambridge, United Kingdom. 373 pages.

External Links

http://www.lpi.usra.edu/meteor/metbull.php - MeteoriticalBulletinDatabase
http:www.lpi.usra.edu/meteor/metbull.php?code=23091 -St. Mary's County@MetBullDatabase
http://adsabs.harvard.edu/full/1973Metic...8R..61N -Early description

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Detailed Mineral List:

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List of minerals arranged by Strunz 10th Edition classification

List of minerals for each chemical element

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St. Mary's County meteorite, St. Mary's Co., Maryland, USA i
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