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Dr Katie Strang
@palaeokatie.bsky.social
Curator of Mineralogy & Petrology at The Hunterian 🏴󠁧󠁢󠁳󠁣󠁴󠁿 Engagement for the Scottish Geology Trust & Director of #ScotGeolFest. Researcher of Scotland’s industrial heritage, coal, taphonomy, coprolites & historic materials.
1.4k followers47 following83 posts
DKpalaeokatie.bsky.social

Rock appreciation - amygdaloidal andesite from the Angus coast, telling a story of violent volcanic eruptions that took place over 400 million years ago 🌋🏴󠁧󠁢󠁳󠁣󠁴󠁿

Landscape photo of a hand palm side up holding an irregularly shaped piece of Devonian andesite. The palm has a cross section of an ammonite tattooed on it. The rock is full of elongated holes (vesicles) which have been infilled with the greenish blue coloured mineral celadonite (amygdules). Around the amygdules are whiteish cream coloured lath shaped phenocrysts of feldspar. The main ground mass (matrix) of the rock is a dark brownish purple colour. The vesicles form when magmas contain dissolved gas. The gas forms bubbles in the magma when the pressure is released on eruption and these bubbles  can end up trapped in the solidified rock. Phenocrysts are formed through different stages of cooling - slow cooling allows larger crystals to form then rapid cooling results in fine-grained ground mass. The amygdules form after the rock has been emplaced, groundwater and/or hydrothermal solutions pass through the rock depositing crystals in the voids which gradually fill up with minerals.
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pattygee.bsky.social

Oh wow, that’s so beautiful!

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HCandyk250.bsky.social

That's great! Awesome ammonite tattoo, too! Also, I love how so many of us are using alt-text as a way to supplement the brevity of posts (while also improving accessibility, of course).

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oh boy that alt text really shines too, ty for the deep explanation!

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Dr Katie Strang
@palaeokatie.bsky.social
Curator of Mineralogy & Petrology at The Hunterian 🏴󠁧󠁢󠁳󠁣󠁴󠁿 Engagement for the Scottish Geology Trust & Director of #ScotGeolFest. Researcher of Scotland’s industrial heritage, coal, taphonomy, coprolites & historic materials.
1.4k followers47 following83 posts