Obsidian is a volcanic glass, not a crystalline mineral. This means it doesn't have a regular, repeating arrangement of atoms like a crystal does. Instead, it's formed when lava cools so quickly that the atoms don't have time to organize themselves into a crystalline structure.

Here's why this matters for the size of crystals:

* Crystals grow by adding atoms in a specific pattern. This pattern creates the characteristic geometric shapes of crystals.

* Obsidian lacks this organized structure. The rapid cooling prevents the atoms from aligning properly, resulting in a disordered, glassy structure.

* Without a repeating pattern, there are no "crystals" to see. Even if there are tiny, localized areas with some order, they're too small and irregular to be visible without magnification.

Think of it like this: Imagine you're building a brick wall. If you have plenty of time, you can carefully place each brick in a precise order, creating a beautiful, regular structure. But if you're rushing, you might just throw the bricks down haphazardly, resulting in a messy pile without any clear pattern. This is similar to how obsidian forms - the rapid cooling creates a messy pile of atoms without the time to form crystals.

Therefore, obsidian isn't about tiny crystals being too small to see. It's about the fundamental lack of a crystalline structure in the first place!