John Faithfull 🌍🇪🇺🏴🧡✊🏻✊🏿<p><a href="https://mastodon.scot/tags/ThinSectionThursday" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>ThinSectionThursday</span></a> Here's a lovely porphyritic camptonite (probably Permian) from North Hoxa, Orkney, seen in plane-polarized light. The large brown crystal is kaersutitic amphibole, the smaller clear crystal near the bottom of the photo is olivine, & the large greyish crystal on the right is clinopyroxene (with a hole in it!). These phenocrysts sit in a finer-grained groundmass of amphibole, clinopyroxene, magnetite & analcime. The field of view is about 2mm wide. <a href="https://mastodon.scot/tags/Geology" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>Geology</span></a> <a href="https://mastodon.scot/tags/Microscopy" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>Microscopy</span></a> <a href="https://mastodon.scot/tags/Orkney" class="mention hashtag" rel="nofollow noopener noreferrer" target="_blank">#<span>Orkney</span></a></p>