Know Your Crystal Hardnesses
Do you know your crystal hardnesses—or even what that means?
I’ve had many conversations over the years with people wanting to know the meaning of a crystal. Often, when I start talking about a crystal's hardness, most will pause and listen. But a few have cut me off with: “I just want the meaning!”
The truth is, if you want to understand your crystals better—whether you're drawn to them for collecting, metaphysical work, or spiritual connection—you need to understand their hardness. It's one of the basic things that can help you learn how to care for them, how to use them, and even why they sometimes change or degrade unexpectedly.
Let me share a story to show you what I mean.
The Case of the Shrinking Sphere
Back in 1991, not long after my mum and dad opened their shop in Pyes Pa (no longer there), a young man came in looking puzzled and concerned. He had bought a lovely aragonite sphere and returned saying, “My crystal has shrunk!”
The polish had worn off, and the sphere was visibly smaller. My dad, who was deeply knowledgeable in minerals, asked him, “What on earth did you do to it?”
The young man replied proudly, “I cleansed it in salt water... for seven days.”
Now, my dad, who was also an avid (salt water) fisherman, paused, then smiled. “You do know salt is corrosive, right?” he said.
And from there, Dad explained about crystal hardness, and how softer minerals often do not react well to salt water. That’s why that poor sphere shrunk—it simply wasn’t tough enough to handle that treatment.
Why Does Hardness Matter?
Crystal hardness is measured on the Mohs Scale of Mineral Hardness, created by Friedrich Mohs in 1812 (ish). It ranks minerals from 1 (softest) to 10 (hardest) based on how easily they can be scratched.
Understanding this scale helps crystal lovers:
Know which stones can go in water or salt.
Understand which ones are suitable for jewellery.
Handle and store their crystals correctly.
Prevent damage when cleansing or using crystals.
The Mohs Scale – A Quick Rundown
Here are the ten main minerals used to define the Mohs Scale:
Talc – Very soft (can be scratched with a fingernail).
Gypsum – Soft and crumbly (used in plaster and drywall).
Calcite – Reacts with acid; soft and easily scratched.
Fluorite – Colourful but delicate.
Apatite – Slightly harder, but still easily damaged.
Orthoclase Feldspar – Found in granite; tougher.
Quartz – Very common, strong, and used in tech and jewellery.
Topaz – Hard and colourful, but tricky to cut.
Corundum – Includes sapphire and ruby, extremely tough.
Diamond – The hardest of all, used in tools and jewellery.
Why This Matters in Real Life
Let’s look at a few crystal-specific examples:
1. Satin Spar Selenite (Hardness: 2)
Satin Spar is often considered strong because of its glow and beauty. But it’s very soft and will scratch or chip easily. Pop it into a pouch with something like Quartz (hardness 7), and it could get bruised or damaged quickly. That’s why it’s not ideal for jewellery or travel.
2. Salt Water and Cleansing
Crystals with a hardness of 7 or above (like Quartz, Topaz, and Diamond) are generally fine in salt water. Plain water is better for crystals with a hardness of 5 and above. Anything softer? Be very careful. They may dissolve, scratch, or lose their polish—like the aragonite sphere I mentioned earlier.
3. Jewellery Choices
Stones like Calcite (3) or Fluorite (4) are beautiful, but they aren’t ideal in rings or bracelets, which get knocked about. They're better for pendants or display pieces. If you want a stone for daily wear, aim for ones rated 6 and up on the Mohs scale.
4. Storage Smarts
If you toss all your crystals together in a bag or box, the harder ones will likely scratch the softer ones. A simple fix? Store them separately or wrap the delicate ones in cloth. It’ll keep your collection looking vibrant and damage-free.
And ya know what,
Understanding the Mohs Scale doesn’t take away from the magic of crystals it adds to it. Knowing the physical properties of your stones lets you connect more deeply with them and care for them with respect. After all, a crystal that is scratched, faded, or broken won’t serve you as well as one that is happy and whole.
So yes, crystal meaning matters, but so does crystal hardness. If you love them, learn about them. They’ll love you back for it.
Photo of a Blue Aragonite Heart, I hope never sees salty water.
Please note that you can find varieties of hardness within some rocks. If you're not sure, ask the person from whom you purchased your crystals. After all, they should know their Mohs scale! ;-).
