Guide to Crystal shapes

Today, we’re going to learn about the different shapes that crystals and minerals can take. Just like snowflakes, no two are exactly alike, but many of them share common shapes that make them special. 

DID YOU KNOW:

In mineralogy, 'crystal habit' is the word used to describe the shape of an individual crystal, or collection of crystals.

Let's look at seven different habits/shapes:

Amorphous

• What It Means: An Amorphous structure means there is no regular shape. These rocks or minerals look more like they’ve been moulded from clay rather than having flat sides.
• Example: Obsidian is amorphous. It's smooth and doesn’t have any particular shape, kind of like jelly! Obsidian is not actually a crystal - it's a volcanic glass!

Geometric Clusters

• What It Means: These crystals grow in groups with similar sizes and shapes, sticking out in all directions like a spiky ball.
• Example: Amethyst often forms geometric clusters that look like purple spikes growing together.

Rhombohedral

• What It Means: This shape is like a stretched cube, pushed out at the corners to form a six-sided shape where all sides are not equal.
• Example: Calcite often forms rhombohedral shapes; it’s like a cube that’s had a twist!

Fibrous

• What It Means: Fibrous crystals look like tiny fibers all packed together, similar to threads in a cloth. They are often so fine that they look like fine hair.
• Example: gypsum spar (selenite) is made up of fibrous crystals. 

Tabular

• What It Means: Tabular crystals form in flat plates or slabs, like little tablets or thin books.
• Example: Barite often comes in tabular shapes, forming stacks of crystals like pages in a book. 

Prismatic

• What It Means: Prismatic crystals are long and skinny with flat, parallel sides, like a bunch of tiny pillars.
• Example: Tourmaline crystals are prismatic, often looking like little gemstone columns.

Banded

• What It Means: Banded describes a crystal 'habit'. It's what's crystals have layers or stripes of different colours or textures.
• Example: Agate is well-known for its beautiful banded patterns, each band a different splash of colour.

Isn’t it amazing how many shapes crystals can form? Next time you’re out exploring or looking at rocks and minerals, see if you can spot these different shapes.

Want to go a bit deeper with your learning? Checkout this great WIKI article. You'll spot some familiar pictures of agate, quartz, pyrite and more!