Fig. 1: Photograph of a red lamprophyre from Iona. Sample 118.087, weight, dimensions, magnetic susceptibility, UTM grid location.
"Rock of the Month # 246, posted for December 2021" ---
Figs. 2-3: Photomicrographs of a sample of Caledonian lamprophyre from Iona. Sample 118.087 is a fine-grained, granular, holocrystalline lamprophyre which occurs as a narrow dyke. This dyke formed by cooling of magma injected into a brittle fracture which propagated through far-older basement rocks, long before the Tertiary volcanism that dominates the scenery of nearby Mull.
In prep.: notes & references, plus petrographic notes and photomicrograph(s) from a new thin section.
Craig,GY (editor) (1965) The Geology of Scotland. Oliver & Boyd, Edinburgh and London / Archon Books, Hamden, CT, 556pp. plus map.
Gillen,C (2013) Geology and Landscapes of Scotland. 2nd edition, Terra Publishing, update of 1st edition of 2003, 260pp.
McKirdy,A (2017) Mull, Iona and Ardnamurchan: Landscapes in Stone. Birlinn Ltd, Edinburgh., printed and bound by Latimer Trend, Plymouth. 48pp.
Ordnance Survey ...
Work of Nick Rock and others on lamprophyres.
Graham Wilson, posted 11 October, 2021
See the Rock of the Month Thematic Index
or, visit the Turnstone "Rock of the Month" Chronological Archives!
|Class/Group/Family||11 rocks from Scotland|
|The "Rock of the Month"|
|Granite||--- #30 --- Ross of Mull granite, Isle of Mull, Scotland|
|Troctolite||--- #31 --- Allivalite, Isle of Rhum, Scotland|
|Diorite||--- #32 --- Appinite, Strontian area, Scotland|
|Marble||--- #51 --- Forsterite marble, Glenelg, Scotland|
|Marble||-- #112 --- Brucite ophicalcite (marble), Isle of Skye, Scotland|
|Monzonite||-- #239 --- Kentallenite, a dark monzonite, Ballachulish area, Scotland|
|Done, or coming soon, five thin sections in prep. (late 2021):|
|Volcanic glass||-- #242 --- Pitchstones from the Isle of Arran, Scotland|
|Diabase||-- #243 --- Crinanite (analcime olivine dolerite / diabase), Isle of Arran, Scotland|
|Gabbro||-- #244 --- "Old Gabbro" of Ardnamurchan, Scotland|
|Volcanic / minor intrusive||-- #245 --- Craignurite, Isle of Mull, Scotland|
|Minor intrusive||-- #246 --- Lamprophyre, Iona, Scotland - "YOU ARE HERE"|