@salt_shack_geology: WHAT IS AN EPIMORPH? 💎 This specimen is quartz. Except the shape you’re looking at… isn’t really quartz-shaped at all. It’s quartz after calcite, and it preserves the geometry of calcite crystals that are no longer there. In this episode, I break down how that can happen. First, calcite grows. Then a later silica-rich fluid coats those crystals in tiny quartz crystals. Then the chemistry changes again, the calcite becomes unstable and dissolves away… while the quartz coating survives. What remains is a hollow shell preserving the shape of the vanished mineral. That is an epimorph. It also gives us a nice reminder that crystal shape can occasionally be deceptive. The chemistry belongs to quartz, the morphology belongs to calcite, and the empty space in the middle records the mineral that used to be there. Mineralogy is basically geology keeping receipts. #Mineralogy #Epimorph #Quartz #Calcite #DefinitionsInDetail

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Friday 18 September 2026 11:34:25 GMT

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Comments

🔔 Bell 🪷 :

wow thank you! and what would it be the calcedony? becuse its seems a mix as well

2026-09-18 11:48:25

Chasing Enigmas :

I love this so much, I wish I had had one, literally one teacher like this in my childhood

2026-09-22 08:53:51

glneahandmede :

So beautiful

2026-09-21 16:11:33

Anqi MineralLab :

Your illustrations very clear, as a Chinese I even can’t fully understand Chinese illustration 🥰

2026-09-23 14:53:34

Bogere Ivan :

wow this is interesting

2026-09-28 17:35:02

(Loulou)Bagheera the houscat :

Omg 😍😍😍 the shape of the specimen is soooo cool!!!

2026-09-19 08:57:42

Salt Shack :

Microcrystalline*

2026-09-18 22:02:01

Kuwa :

Always calcite doing some crazy shit bro[Crying]

2026-09-18 22:26:50

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