Amethyst’s Mohs Hardness
Amethyst is a purple variety of quartz, a common mineral found in many geological settings. Its strength refers to its resistance to scratching and breaking. Understanding these physical properties helps appreciate its use in jewelry and decorative objects.
The Mohs scale of mineral hardness provides a standard measure of a material’s scratch resistance. This scale ranges from 1 to 10, with 1 being the softest (like talc) and 10 being the hardest (diamond). Amethyst consistently ranks at a 7 on this scale, placing it among the more durable gemstones for everyday wear.
A Mohs hardness of 7 indicates amethyst is resistant to scratching from many common materials. For instance, it can scratch glass, which has a hardness of around 5.5. However, materials harder than 7, such as topaz (8), sapphire (9), or diamond (10), can scratch amethyst. Common household dust, often containing tiny quartz particles, can also cause microscopic scratches over time if not handled carefully.
What Else Impacts Amethyst’s Durability?
Beyond scratch resistance, a gemstone’s overall durability involves its resistance to breaking, chipping, and environmental factors. Amethyst, like all quartz varieties, exhibits no cleavage. This means it does not break along defined planes, but rather fractures in a conchoidal, or shell-like, pattern. This characteristic contributes to its relative toughness against impacts, making it less prone to breaking into large pieces compared to gems with perfect cleavage.
Despite its toughness, amethyst is considered brittle. While it resists breaking along flat planes, a strong, sudden impact can still cause it to chip or fracture. For example, dropping an amethyst ring onto a hard surface could result in damage, even with its Mohs hardness of 7. While resistant to shattering, care is still necessary.
Amethyst is also sensitive to certain environmental conditions, particularly heat. High temperatures can cause the purple color to fade or even change entirely, sometimes turning yellow to become citrine. This color change is permanent, so it is important to keep amethyst away from extreme heat sources. Rapid temperature changes can also stress the stone, potentially leading to fractures.
Prolonged exposure to direct sunlight can also cause the vibrant purple hues to lighten and fade. While resistant to common household chemicals, strong acids or alkaline solutions should be avoided, as they could damage the stone’s surface or luster.
Protecting Your Amethyst
Proper care and storage maintain amethyst’s beauty and integrity. When wearing amethyst jewelry, remove it during strenuous activities or tasks that might expose it to impacts or harsh chemicals. This includes gardening, cleaning, or sports. Protecting the stone from direct blows helps prevent chips and fractures.
Storing amethyst jewelry correctly also helps preserve its condition. It should be kept separate from harder gemstones, such such as diamonds or sapphires, to prevent them from scratching its surface. Storing amethyst in a soft cloth pouch or a separate compartment within a jewelry box can protect it from both harder and softer materials. Keeping it away from direct sunlight and sources of heat, like radiators or window sills, will also help prevent color fading.
Cleaning amethyst is a straightforward process that should be done gently. Using mild soap, lukewarm water, and a soft brush is sufficient to remove dirt and grime. After cleaning, rinse the stone thoroughly with clean water and dry it with a soft, lint-free cloth. Ultrasonic cleaners are not recommended, especially for amethyst with internal fractures or delicate settings, as vibrations could worsen flaws or dislodge the stone. Steam cleaners should also be avoided due to the risk of thermal shock.