I couldn't get the link to work for archwilio (Gwynedd archaeological trust website)
So I have added what they say here:
Description :
Recorded 6" OS.
Maen Hir, 500 SE Hirdrefaig 8 1/4' high x 4' x 1 3/4', with packing stones at base.
As described by RCAHM. Published survey 25" correct.
Somewhat blocky slab with a pronounced lean to W. Local igneous stone with quartz veins. Packing stones on W side. Stands on a rounded E-W ridge – ridge obscures view to EW somewhat. Visible for some distance on both sides of the ridge – most on N & NW where it is on skyline for some places.
The monument comprises a large standing stone that probably dates to the Bronze Age (c.2300 – 800 BC). It is located within an enclosed field of improved pasture on an E-W aligned ridge. The standing stone measures 2.5m tall, 1.4m wide and 0.5m in depth. It is aligned N-S and has a weathered surface. The stone leans to the W. There are packing stones visible on the W side. The stone is made of a local igneous rock and is notable for its quartz veins.
A standing stone of probable Bronze Age date. The stone is 2.5m tall, 1.4m wide and 0.5m deep. It is aligned north-south and has a weathered surface and rectangular profile with parallel sides that rise to a bluntly rounded point.
Sources :
Prehistoric Funerary and Ritual Monument Survey: West Gwynedd & Anglesey , Smith, G. , 2003 ,
SH47SE , Ordnance Survey , 1963 ,
Inventory of the Ancient Monuments of Anglesey , Royal Commission on Ancient and Historic Monuments , 1937 ,
SH47SE 12 , Ordnance Survey , 1970 ,
Prehistoric Anglesey , Lynch, F. , 1970 ,
Hirdre-Faig Standing Stone , Cadw , 2006 ,
Hirdre-Faig Standing Stone , Berry, J. , 2006 ,
Gwalchmai Booster to Bodffordd Link Water Main and Llangefni to Penmynydd Replacement , Evans, R. T. J. , 2008 ,
Events :
40758 : Gwalchmai Booster to Bodffordd Link Water Main and Llangefni to Penmynydd Replacement (year : 2008)
40526 : Prehistoric Funerary and Ritual Monument Survey: West Gwynedd/Anglesey (year : 2003)