|Latitude & Longitude (WGS84):||53° 2' 11'' North , 4° 19' 10'' West|
|Latitude & Longitude (decimal):||53.03639,-4.31972|
|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|
|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|
|British Isles||Group of Islands|
Select Mineral List TypeStandard Detailed Strunz Dana Chemical Elements
4 valid minerals.
Meteorite/Rock Types Recorded
Select Rock List TypeAlphabetical List Tree Diagram
Entries shown in red are rocks recorded for this region.
Detailed Mineral List:
|ⓘ 'Albite-Anorthite Series'|
|ⓘ 'Clinopyroxene Subgroup'|
|ⓘ 'Fayalite-Forsterite Series'|
|ⓘ 'Pyroxene Group'|
List of minerals arranged by Strunz 10th Edition classification
|Group 1 - Elements|
|Group 2 - Sulphides and Sulfosalts|
|Group 9 - Silicates|
|Unclassified Minerals, Rocks, etc.|
List of minerals arranged by Dana 8th Edition classification
|Group 1 - NATIVE ELEMENTS AND ALLOYS|
|Semi-metals and non-metals|
|Group 2 - SULFIDES|
|AmXp, with m:p = 1:1|
|Group 51 - NESOSILICATES Insular SiO4 Groups Only|
|Insular SiO4 Groups Only with all cations in octahedral  coordination|
|Group 65 - INOSILICATES Single-Width,Unbranched Chains,(W=1)|
|Single-Width Unbranched Chains, W=1 with chains P=2|
|Unclassified Minerals, Mixtures, etc.|
List of minerals for each chemical element
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
419.2 - 443.8 Ma
|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. 
443.8 - 485.4 Ma
511 - 541 Ma
|Lower Cambrian Rocks (Undifferentiated)|