Gold is soft in its pure form.
While gold is a strong metal, its defining characteristic is its malleability, making it the most malleable of all metals. This means pure gold is easily shaped and deformed. However, this softness makes it unsuitable for many practical applications without being alloyed with other metals.
Why is Pure Gold Soft?
The softness of gold stems from its atomic structure. Gold atoms have a weak attraction to each other, allowing them to slide past one another relatively easily when force is applied. This characteristic contributes to its malleability and ductility.
How Alloys Harden Gold
To increase gold's durability and strength for jewelry and other uses, it's commonly alloyed (mixed) with other metals. Common alloying metals include:
- Silver: Increases hardness and can lighten the color.
- Copper: Increases hardness and adds a reddish hue.
- Nickel: Increases hardness and can create white gold when combined with other metals like zinc.
- Zinc: Used in combination with other metals to influence color and hardness.
The karat system indicates the proportion of gold in an alloy. 24 karat (24K) gold is pure gold, while lower karat values (e.g., 18K, 14K) indicate a lower percentage of gold and a higher percentage of other metals. The lower the karat, the harder and more durable the gold alloy becomes. For example, 14K gold is much harder than 24K gold.
Gold Hardness Table (Illustrative)
| Karat | Gold Purity (%) | Hardness (Mohs Scale - Approximate) | Characteristics |
|---|---|---|---|
| 24K | 99.9% | 2.5 - 3 | Very soft, easily scratched and bent. |
| 22K | 91.7% | ~3 | Relatively soft, less prone to scratching than 24K. |
| 18K | 75% | ~3.5 | More durable than 22K or 24K, suitable for some jewelry. |
| 14K | 58.3% | ~4 | Significantly harder and more durable, commonly used in jewelry. |
| 10K | 41.7% | ~4.5 | Hardest gold alloy commonly used in jewelry, very durable. |
Note: Mohs Hardness Scale is a relative scale and these are approximate values as hardness varies based on specific alloy composition.
