Latitude & Longitude (WGS84):	53° 2' 11'' North , 4° 19' 10'' West
Latitude & Longitude (decimal):	53.03639,-4.31972
GeoHash:	G#: gckvtwyrr
Locality type:	Meteorite Fall Location
Meteorite Class:	Winonaite meteorite
Meteoritical Society Class:	Winonaite
Metbull:	View entry in Meteoritical Bulletin Database
Köppen climate type:	Cfb : Temperate oceanic climate
Nearest Settlements:	Place Population Distance Penygroes 1,793 (2017) 3.1km Talysarn 1,086 (2017) 4.6km Groeslon 880 (2017) 5.4km Garndolbenmaen 101 (2012) 8.8km Bontnewydd 951 (2017) 9.5km
Other/historical names associated with this locality:	Caernarvonshire

Winonaite (Primitive Achondrite); Shock Level-S2.
Fell 14 April 1931, 157 g.

Although the main mass is reported to have fallen into the sea, a moderately small portion was recovered. The Pontlyfni meteorite exhibits a fine-grained texture rich in both magnesium-rich olivine (Fa1) and pyroxene (Fs2). Troilite is also relatively abundant. Minor amounts of clinopyroxene, plagioclase and Fe-Ni metal are also found as well as rare relic chondrules. For several decades Pontlyfni was recognized as a somewhat unusual meteorite, but its similarities to a small group of primitive achondrites called Winonaites were not recognized until relatively recently. The Winonaites have very reduced mineralogical assemblages and their oxygen isotopes appear to be closely related to those found in the silicate inclusions of the IAB complex Irons. As most Winonaites lack chondrules, but have a chemical compositions that belies extensive differentiation they have been deemed 'primitive achondrites.' However, the overall similarities between Pontlyfni and other Winonaites are compelling and so Pontlyfni is now classified as a Winonaite. This has two unusually peculiar consequences. The belated classification makes Pontlyfni the only observed Winonaite fall (whenever possible, meteorite prototypes are selected from the members whose falls were observed). And, Pontlyfni is now a chondrule-containing meteorite stone formally assigned to the class of 'achondrites.'

While all Winonaites have fine-grained reduced mineralogical assemblages, Pontlyfni's constituents are more olivine-rich, its textures are even finer-grained, and its mineralogical assemblages more reduced than those of other Winonaites. Odd irregular aggregates are also found. Some of Pontlyfni's features have been attributed to incipient partial melting — but Pontlyfni's history and its precise relationship to other Winonaites are still matters of ongoing discussions.

Regions containing this locality

Eurasian Plate	Tectonic Plate
Europe	Continent
British Isles	Group of Islands

Regional Geology

This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.

Click on geological units on the map for more information. Click here to view full-screen map on Macrostrat.org

Silurian 419.2 - 443.8 Ma ID: 3185808	Paleozoic sedimentary rocks Age: Silurian (419.2 - 443.8 Ma) Lithology: Sedimentary rocks Reference: Chorlton, L.B. Generalized geology of the world: bedrock domains and major faults in GIS format: a small-scale world geology map with an extended geological attribute database. doi: 10.4095/223767. Geological Survey of Canada, Open File 5529. [154]
Ordovician 443.8 - 485.4 Ma ID: 3148570	Ordovician limestone Age: Ordovician (443.8 - 485.4 Ma) Lithology: Limestone Reference: Asch, K. The 1:5M International Geological Map of Europe and Adjacent Areas: Development and Implementation of a GIS-enabled Concept. Geologisches Jahrbuch, SA 3. [147]
Early Cambrian 511 - 541 Ma ID: 2030875	Lower Cambrian Rocks (Undifferentiated) Age: Cambrian (511 - 541 Ma) Lithology: Mudstone, siltstone and sandstone Reference: British Geological Survey. DiGMapGB-625. British Geological Survey ©NERC. [23]

Data and map coding provided by Macrostrat.org, used under Creative Commons Attribution 4.0 License

References

External Links