Tags: Site Of Special Scientific Interest.
Halkyn Common and Holywell Grasslands (Welsh: Comin Helygain a Glaswelltiroedd Treffynnon) is a Site of Special Scientific Interest in Flintshire north Wales covering Halkyn Mountain and surrounding areas. It lies 4 km north-west of Mold on a plateau about 100-300 m above sea-level. It includes 699.3 hectares of grassland heathland and other open vegatation with numerous spoil tips and quarries.