Is Obsidian Harder Than Diamond? A Deep Dive

Is Obsidian Harder Than Diamond? No, obsidian is not harder than diamond. Diamond ranks 10 on the Mohs hardness scale, while obsidian, a volcanic glass, is much softer, typically around 5-6.

You may have heard claims that obsidian, with its razor-sharp edges, is harder than diamond.

Many people assume that since obsidian can cut so well, it must be one of the hardest materials on Earth. But is that really true?

The simple answer is no—obsidian is not harder than diamond. Diamond is the hardest naturally occurring substance, ranking at the top of the Mohs hardness scale.

In contrast, obsidian, a type of volcanic glass, is much softer, ranking only around 5-6 on the Mohs scale. But hardness isn’t the only factor when comparing these materials.

Obsidian’s sharpness, brittleness, and ability to break into fine edges make it unique, while diamond’s extreme hardness makes it useful for cutting, drilling, and even industrial applications.

In this article, you’ll explore the real differences between obsidian and diamond, learn why people get confused, and understand their practical uses in various industries. [Is Obsidian Harder Than Diamond?]

What is Hardness? The Mohs Hardness Scale Explained

When discussing how hard a material is, scientists use a standard called the Mohs Hardness Scale.

What is the Mohs Hardness Scale?

The Mohs Hardness Scale was developed in 1812 by Friedrich Mohs, a German geologist, to compare how well materials resist scratching.  [Is Obsidian Harder Than Diamond?]

The scale ranks minerals from 1 (softest) to 10 (hardest) based on their ability to scratch other substances. [Is Obsidian Harder Than Diamond?]

• Talc (1) – The softest mineral, easily scratched by a fingernail.
• Gypsum (2) – Can also be scratched with a fingernail.
• Calcite (3) – Can be scratched with a copper coin.
• Fluorite (4) – Slightly harder, can be scratched by a knife.
• Apatite (5) – The hardness of human teeth.
• Obsidian (5-6) – Harder than glass but still relatively soft.
• Quartz (7) – A common mineral found in sand.
• Topaz (8) – Very hard and often used in jewelry.
• Corundum (9) – Includes rubies and sapphires.
• Diamond (10) – The hardest naturally occurring material, capable of scratching all others.

Since obsidian ranks at 5-6 and diamond at 10, it’s clear that diamond is significantly harder. [Is Obsidian Harder Than Diamond?]

Why Does Hardness Matter?

Hardness determines how well a material resists scratching and wear. This is why diamond is used in industrial cutting tools—because no other naturally occurring substance can scratch it.

Obsidian, on the other hand, can be scratched by materials like quartz and steel. [Is Obsidian Harder Than Diamond?]

Obsidian vs. Diamond: Key Differences

Obsidian and diamond are two fascinating materials, but they have completely different compositions, structures, and uses.

1. Composition

• Obsidian is a volcanic glass, formed when lava cools too quickly for crystals to develop. Because it lacks a structured atomic arrangement, it is classified as an amorphous solid.
• Diamond is made of pure carbon, where the atoms are arranged in a crystalline lattice. This strong bonding structure is what makes diamond the hardest material.

2. Structure and Strength

• Obsidian has an irregular molecular structure, which makes it fragile. It can break or chip easily, forming extremely sharp edges.
• Diamond has a perfect crystalline structure, making it incredibly hard but not unbreakable. If struck with force, a diamond can chip or shatter due to its internal cleavage planes.

3. Hardness vs. Toughness

People often confuse hardness with toughness:

• Hardness = Resistance to scratches (Diamond wins)
• Toughness = Resistance to breaking (Obsidian is more brittle)

While diamond is much harder, obsidian’s brittle nature allows it to break into razor-sharp edges, making it useful for cutting tools. [Is Obsidian Harder Than Diamond?]

Why Do People Think Obsidian is Harder Than Diamond?

1. Obsidian Can Be Sharper Than Diamond

One of the main reasons people think obsidian is harder than diamond is because of how sharp it can be.

When fractured, obsidian creates an edge that is sharper than even the finest steel scalpels.  [Is Obsidian Harder Than Diamond?]

In fact, some surgeons prefer obsidian blades for specific types of surgery because they can make cleaner, more precise cuts with less tissue damage compared to traditional steel scalpels.

Why is obsidian so sharp?

• Obsidian has an amorphous structure, meaning it lacks a crystalline arrangement like diamonds.
• When it breaks, it undergoes conchoidal fracturing, a process that results in extremely fine, sharp edges at the molecular level.
• These edges can be as sharp as three nanometers, much thinner than steel or even a honed diamond blade.

But does sharpness equal hardness?

No. While obsidian’s edges can be sharper than those of diamond, sharpness is not the same as hardness.  [Is Obsidian Harder Than Diamond?]

Hardness refers to a material’s ability to resist scratches, and on that front, diamond is far superior. Obsidian, ranking 5-6 on the Mohs scale, is much softer than diamond, which ranks 10.

This means that while obsidian can cut efficiently, it is also prone to scratches and breakage much more easily than diamond. [Is Obsidian Harder Than Diamond?]

2. Movies and Video Games Spread Misinformation

Another major reason for this misconception is how obsidian is portrayed in popular culture, video games, and movies.

Many fictional stories depict obsidian as a nearly indestructible material, which is far from the truth. [Is Obsidian Harder Than Diamond?]

Examples from Pop Culture

• Minecraft – In the popular game, obsidian is one of the toughest blocks, requiring a diamond pickaxe to break it. This suggests that obsidian is stronger than diamond, which is not true in real life.
• Fantasy Novels & Movies – In many fantasy stories, obsidian weapons are portrayed as nearly indestructible, when in reality, they are quite fragile.

Reality Check

• In real life, obsidian is brittle. If you drop an obsidian blade, it is likely to shatter into pieces because it lacks the structural integrity of crystalline materials like diamond.
• Unlike in video games, where obsidian appears to be unbreakable, actual obsidian can be scratched by common materials like quartz (Mohs 7) or even a steel nail.

These fictional portrayals have led many people to assume that obsidian is tougher and harder than it actually is. [Is Obsidian Harder Than Diamond?]

3. People Confuse Hardness with Cutting Ability

A major reason why people assume obsidian is harder than diamond is a simple misunderstanding of what hardness actually means. [Is Obsidian Harder Than Diamond?]

Hardness vs. Sharpness vs. Strength

People often use the terms “hardness,” “sharpness,” and “strength” interchangeably, but they actually mean very different things:

• Hardness = A material’s resistance to being scratched (measured by the Mohs scale).
• Sharpness = How fine and precise an edge a material can achieve.
• Toughness (or Strength) = How well a material resists breaking or shattering under impact.

Diamond is extremely hard, meaning it resists scratches better than any other material. However, it is not the toughest material, meaning it can still chip or break under extreme force.

Obsidian, on the other hand, is softer but can form extremely sharp edges. However, it is far less durable and will break much more easily than diamond.  [Is Obsidian Harder Than Diamond?]

A Real-World Example

• A piece of obsidian can cut through soft materials (like skin) better than diamond, but it can also be scratched by common materials like quartz or steel.
• A diamond knife edge may not be as sharp as an obsidian blade, but it will last far longer without getting damaged.

Understanding this difference helps clear up the misconception about obsidian’s hardness. [Is Obsidian Harder Than Diamond?]

Practical Uses of Obsidian and Diamond

Despite the differences in hardness, both obsidian and diamond have unique properties that make them valuable in various industries. [Is Obsidian Harder Than Diamond?]

How is Obsidian Used?

Even though obsidian is brittle, it has been used for thousands of years for its sharpness and natural beauty.

1. Ancient Tools & Weapons

• Obsidian was one of the first materials used by early humans to make arrowheads, knives, and spear tips.
• Because it breaks into incredibly sharp edges, it was the preferred choice for cutting tools in many ancient civilizations, including the Aztecs and Native American tribes.

2. Modern Surgery

• Some surgeons today still use obsidian scalpels for delicate procedures.
• An obsidian blade is smoother and sharper than a steel scalpel, which can reduce tissue damage and promote faster healing.

3. Jewelry & Decor

• Obsidian is a popular semi-precious gemstone, often used in rings, necklaces, and carvings.
• However, due to its brittle nature, it is not as durable as diamond, making it more susceptible to scratches and breakage over time.

How is Diamond Used?

Because of its extreme hardness, diamond has a wide range of applications beyond just jewelry.

1. Jewelry

• Diamonds are the most popular gemstone for engagement rings and fine jewelry.
• Their extreme hardness ensures they stay brilliant and scratch-free for a lifetime.

2. Industrial Cutting Tools

• Diamond-tipped saws, drill bits, and grinders are used in construction and mining.
• These tools can cut through rock, metal, and even other diamonds.

3. Scientific Instruments

• Diamond anvils are used in laboratories to create extremely high-pressure environments for scientific research.
• These anvils help scientists study the properties of materials under extreme conditions

See more: Is Sonography Harder Than Radiography?

FAQs: Common Questions About Obsidian and Diamond

Can obsidian cut diamond?

No, obsidian is not hard enough to scratch or cut diamond. However, it can be sharper than diamond when fractured into thin edges.

Is obsidian stronger than steel?

No, obsidian is not stronger than steel. While it can be sharper, it is brittle and breaks easily under pressure.

Can diamond break?

Yes, despite being the hardest material, diamond is not indestructible. A sharp impact can cause it to chip or shatter.

Why is obsidian so sharp?

Obsidian fractures in a way that creates microscopically thin edges, making it sharper than most metals.

Can obsidian be used for jewelry like diamonds?

Yes, but obsidian is more fragile than diamond and can scratch easily. It is mainly used in decorative pieces rather than everyday jewelry.

Conclusion: Is Obsidian Harder Than Diamond?

Now you know the truth—obsidian is not harder than diamond. While obsidian can be sharper when fractured, it is much softer (Mohs 5-6) and more brittle than diamond.

Diamond, ranking 10 on the Mohs scale, is the hardest naturally occurring material and can scratch any other substance, including obsidian. [Is Obsidian Harder Than Diamond?]

So, next time you hear someone say obsidian is harder than diamond, you can confidently correct them. Obsidian is sharp, but diamond is the hardest!