Amethyst Geode

Splashery stretches a drumhead over this Splash's outline, twelve inches across, and finds the ways it can ring. Its lowest is 531.3 Hz, 26 cents sharp of C5. The next fifteen are its overtones, and each one draws its own figure: sand gathers on the lines that stay still.

Tap to open or close it. Hands-on: swing the front half open or shut by hand.

A geode is a rock with a hollow inside, lined with crystals. Over a very long time, water full of dissolved minerals seeped into the hollow, and the crystals slowly grew inward from the walls. Amethyst is purple quartz; its color comes from a little iron in the crystal.

The geode starts open. Tap it to close it; tap again and it opens, its halves swing wider, and the crystals glow violet with twinkling tips, then settle. Some amethyst geodes from Brazil and Uruguay are taller than a person. With ✋ Hands-on on, swing the front half open or shut by hand on its hinge; it stays where you leave it, and shut, the two halves fit together.

Made in Splashery. Its code is MIT.

This link opens it in the Playground. To put it on your own page, add the element and one script tag. Every option.