Nature Stones: Grape Agate, Quartz, And Amethyst

Nature Stones: Grape Agate, Quartz, And Amethyst

Grape Agate: What Is It?

Grape agate is a trading name for purple aggregates of microscopic quartz crystals with a spherical (botryoidal) shape. The name refers to their purple hue and the fact that they grow in clusters like bunches of grapes. This material was discovered in the Mamuju region, close to the western shore of the Indonesian island of Sulawesi.

Grape agate was first introduced to the mineral market in 2016. It immediately gained appeal at mineral exhibits, rock stores, websites, and internet marketplaces. Specimens with an amusing look and an intriguing name, like the grape agate market.

These specimens have little “grapes.” They are from two to eight millimeters in diameter. Although purple is the most appropriate hue for the “grape” name, other examples feature white, gray, green, or blue fruits.

Yes, grape. Perhaps Not Agate.

As a marketing word, the term “grape agate” has remained. The name, however, is a misnomer. Misnomers are false scientific names. There are no disagreements with the term “grape” due to its purple hue. However, others disagree with the term “agate” as a species/variety name. Here is a breakdown…

Agate Grape:

This is an incorrect term for agate since agate should have parallel internal banding. Although the term agate also refers to quartz with a microcrystalline structure, most grapes have a drusy surface, which makes them megascopically crystalline.

Chalcedony Grape:

As with agate, chalcedony refers to quartz having a microcrystalline texture.

Citrus Quartz:

Quartz is a more appropriate term than agate or chalcedony. However, the correct term for purple quartz is amethyst.

Amethyst with Botryoidal Crystals:

The term “amethyst” is more accurate in mineralogical and gemological definitions, whereas the adjectival form “botryoidal” conveys a rounded shape.

Thus, this author thinks that the term “botryoidal amethyst” is technically true but lacks the appeal of “grape agate.”

What exactly is quartz?

Quartz is a chemical compound composed of one silicon atom and two oxygen atoms. That would be silicon dioxide (SiO2). It is the most plentiful mineral on the planet, and due to its unique qualities, it is one of the most useful natural compounds.

What Is the Origin of Quartz?

Quartz is the most plentiful and extensively dispersed mineral on the surface of the Earth. It is widespread and abundant across the planet. It crystallizes at all temperatures. It is widely distributed across igneous, metamorphic, and sedimentary rocks. It is very resistant to weathering, both mechanical and chemical. Due to its toughness is the main mineral on mountaintops and the predominant component of beach, river, and desert sand. Quartz is widespread, abundant, and durable. The globe over, mineable reserves have been discovered.

Amethyst: What is it?

Amethyst is the most notorious purple gemstone in the world. For almost 2000 years, the purple form of quartz has been utilized in personal decoration.

Amethyst is the February birthstone and a significant New Age jewel. It is used to create faceted stones, cabochons, beads, tumbling stones, and a variety of other jewelry and decorative products.

Amethyst has a Mohs stiffness of 7 and is cleavage resistant. As a result, it is strong enough to be used in rings, bracelets, earrings, pendants, and other types of jewelry. Massive amethyst deposits in South America and Africa ensure that the price of amethyst remains low. The majority of individuals can afford amethyst.

Amethyst’s color

Amethyst is a very famous gemstone due to its beautiful purple hue. As with the term “turquoise,” the term “amethyst” is now used to refer to both a hue and a kind of gemstone.

While the term “amethyst” conjures up images of a dark purple gemstone, amethyst exists in various purple hues. Purple may be very faint and hardly visible or extremely dark and practically impenetrable. It is available in reddish-purple, purple, and violetish-purple shades. Amethyst is available in a variety of hues.

Today, most light amethyst is cut into little calibrated stones for mass-market jewelry. Most amethyst in the premium reddish-purple tint is utilized in high-end or designer jewelry.

The creative community has come up with a slew of terms to describe the many colors of amethyst. Orchids and lavender are good choices for lighter colors; grape, indigo, or royal are good choices for deeper hues; and raspberry or plum are good choices for reddish colors. While these designations help communicate a broad sense of hue, they are far from accurate or universally recognized.

Amethyst is a popular stone by artisans, jewelers, crafters, and consumers due to its mix of appealing hues, high durability, and affordability.

Crystals of Amethyst

The process through which amethyst acquires its purple hue starts during crystal formation. This occurs when trace quantities of iron are absorbed into the crystallization process of quartz. Gamma rays released by radioactive elements inside the host rock irradiate the iron, resulting in the purple tint.

The intensity of amethyst’s purple hue varies depending on the crystal section. These color changes, referred to as “color zoning,” are created by the crystal incorporating variable quantities of iron at various phases of crystal formation.

Amethyst crystals develop slowly, and the fluids supplying the iron and silica required for crystal formation might vary in composition. The deepest shade of amethyst occurs when the crystal grows with the greatest quantity of iron. This results in color zoning.

Color zoning affects amethyst’s marketability and value. The majority of individuals want a vibrant and consistent stone in color. Consequently, stones with consistent hue – that is, without color zoning – are the most sought and precious.

Amethyst Color Zoning:

Amethyst crystals develop slowly, and the liquids from which they form might alter in composition over time. As the water’s composition varies, varied iron levels are integrated into the crystal’s surface. Later on, radiation released by minerals in the surrounding rock modifies the iron, giving it a purple hue.

This can result in zones of varying color intensity within the crystal. Each of these zones corresponds to a period in the crystal’s development, much like the growth rings of a tree. The diamond seen above has spectacular color zoning. While this is fascinating geologically, the most desirable amethyst stones have a deep, uniform hue.

Amethyst’s Physical Properties

Amethyst’s physical attributes are almost equal to those of other color variants of quartz. The only significant distinction is in the material’s color.

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