|McIlroy's Port to Portmuck, Island Magee||Antrim|
|McIlroy’s Port to Portmuck, Islandmagee, Co.Antrim, June 1997.|
|Site Type: ||Coastal section|
|Site Status: ||ASSI|
|District: ||Larne Borough Council|
|Grid Reference: ||D34544027|
|Rock Age: ||Tertiary|
|Rock Name: ||Antrim Lava Group|
|Rock Type: ||Amydaloidal Basalt, Pegmatite, Picrite|
|Minerals: ||Natrolite, Sodalite, Titanaugite|
|Other interest: ||dyke, volcanic vent, No Data|
Summary of site:
There is a lava flow at this locality containing a high proportion of the mineral olivine. Such lavas are described a picrites and, unusually in this one, there is a 30 cm thick zone containing coarsely crystalline patches and veins. These patches and veins are pegmatites, usually created in the final stages of igneous activity when high levels of volatiles create cavities and circumstances in which large crystals, exceeding 2.5 cm long, can grow. This pegmatite is noted for the occurrence of a rare mineral, sodalite, a chlorinated sodium aluminium silicate belonging to a group called feldspathoids, similar in structure to feldspars but containing less silica.
For a description of the context of these minerals, see the general account for McIlroy's Port, record 640.