# @stem_antics on Instagram

- **Type:** Video
- **Original URL:** https://www.instagram.com/p/DU3ceoNjw1S
- **Gondola URL:** https://gondola.cc/posts/61935930-stem-antics-instagram
- **Thumbnail:** https://img.gondola.cc/tr:w-,h-,fo-auto/postThumbnails/13ba4f4073.jpg
- **Posted:** 2026-02-17T16:51:19.000+00:00
- **Account Owner:** Stem Antics (@stem_antics) — https://gondola.cc/stem_antics

## Caption

This is a septarian nodule — a 50–70 million year old geological puzzle.

Here’s how it forms:

• 🌊 It starts as mud on an ancient sea floor.
• 🦠 As the mud hardens, minerals like calcite begin to cement it into a round nodule.
• 🌎 The nodule shrinks and cracks (often from dehydration or pressure changes).
• 💧 Groundwater seeps into the cracks.
• 💎 Minerals like calcite or aragonite crystallize inside — forming these yellow crystal pockets.

The dark brown lines? Usually aragonite.
The yellow crystals? Often calcite.
The gray outer rock? Limestone or mudstone.

Why this is cool 👇
You’re literally looking at ancient chemistry + physics frozen in time:
• Crystal growth from supersaturated mineral water
• Stress fractures from compaction
• Self-organizing mineral patterns

Nature basically 3D-printed this… millions of years ago.

Would you crack one open or leave it sealed? 👀
Comment what you think caused the cracks — pressure or drying?

#STEM #GeologyRocks #EarthScience #Minerals #Crystals ScienceIsCool

## Stats

- **Views:** 9,878
- **Likes:** 326
- **Shares:** 0
- **Comments:** 5

## Tags

stem, geologyrocks, crystals, minerals, earthscience

---
Copyright (c) Gondola