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Proustite Gemstone: Properties, Meanings, Value & More

プルースタイトの宝石：特性、意味、価値など

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Proustite is a scarlet red gemstone known as a significant metal ore. What is proustite an ore of? Silver!

Is proustite a mineral? Yep, proustite is a silver arsenic sulfide mineral.

Is proustite rare? Definitely. Silver is already rarely a native element in minerals. Silver minerals are also rarely faceted and rarely attractive, making the ruby-red proustite sought-after by collectors.

Today, we’ll cover proustite’s gemstone and mineral properties, meanings, history, prices, and more!

Image credit: Rob Lavinsky, iRocks.com – CC-BY-SA-3.0

What is Proustite?

Proustite is a rare semi-precious gemstone with deep scarlet hues. Astrologically, proustite benefits Sagittarius.

Nicknames for proustite include:

• Ruby silver

• Ruby silver ore

• Light red silver

• Light red silver ore

• Light ruby silver ore

• Red silver ore

• Arsenical red silver

• Arsenical silver blende

• Sangre de torro (Spanish for “blood of the bull”)

Note: Proustite’s “ruby” nicknames are only referencing its color; ruby is a separate mineral.

Obviously, proustite is a silver ore. But “ruby silver” can also refer to polybasite, pearceite, and pyrargyrite. Pyrargyrite is also called “dark red silver” or “dark red silver ore.”

On that note, what are the uses of proustite?

Proustite Uses

The predominant industrial use of proustite is as a source of silver. It’s not the most common silver ore today (that would be argentite), as it was more important historically, but it’s still a minor ore.

As of 2022, the top silver uses outside of jewelry and silverware were for electronics and electrical components (including solar energy), catalysts, and metal solders.

Additionally, proustite has been synthesized and studied for dye laser optical mixing.

Image credit: Rob Lavinsky, iRocks.com – CC-BY-SA-3.0

Proustite Specifications & Characteristics

The mineral proustite is composed of silver, sulfur, and arsenic. It’s classified as a sulfosalt mineral.

Proustite forms a series with silver antimony sulfide pyrargyrite. Though very similar, pyrargyrite is darker red with a purplish-red streak.

Pyrargyrite is in the proustite mineral group alongside xanthoconite and pyrostilpnite. Xanthoconite has the same composition as proustite but monoclinic crystal structure.

Proustite crystals are often horizontally striated. They can be prismatic, rhombohedral, and/or scalenohedral (twelve scalene triangle-shaped faces). Some prismatic crystals have one scalenohedral termination and one rhombohedral termination.

Twinning is common. Multiple proustite crystals can be found forming blocky groups, trillings (three crystals intergrown), or interpenetrating each other.

The proustite mineral can also occur in compact, encrusting, massive, grainy, botryoidal, or globular forms.

Proustite properties listed:

• Mohs hardness: 2-2.5

• Color: Shades of deep red (scarlet, vermilion, cherry), dark purplish- or violet-red, reddish-gray, gray, metallic gray

• Crystal structure: Hexagonal (trigonal)

• Luster: Adamantine or submetallic

• Transparency: Translucent to opaque, rarely transparent; Can become more opaque over time

• Refractive index: 2.792-3.088

• Density: 5.51-5.64

• Cleavage: Distinct/good on {1011}

• Fracture: Conchoidal or uneven/irregular

• Streak: Scarlet or vermilion red

• Luminescence: None

• Pleochroism: Present & moderate to strong in blood-red and scarlet

• Birefringence: 0.295-0.296

• Dispersion: Weak

• Optical phenomena: Often irreversible photochromism

What’s that “irreversible photochromism” about?

Image credit: Parent Géry, Public Domain

Proustite Changes Over Time

One of proustite’s notable (though unfortunate) qualities is photochromism.

Photochromism is when a mineral changes color from exposure to light. Unlike color-changing gems like alexandrite, photochromic gems only change color under UV light (like sunlight) and the shift happens at various rates, from minutes to hours after exposure.

Another important distinction is reversible photochromism (tenebrescence) vs irreversible photochromism. Tenebrescent stones (e.g. hackmanite) can change color back and forth indefinitely. Stones with irreversible photochromism (e.g. kunzite) permanently change color upon exposure.

Proustites containing silver have irreversible photochromism; light exposure will make them darker in color (eventually black) and more opaque. It can also cause a dull, dark film on the crystal’s surface, but you can remove the film with a simple cleaning.

Even without light exposure, proustites can still gradually darken over time. The reason is because the mineral’s silver atoms are somewhat free-flowing, so they can start forming another crystal inside: dark gray acanthite. Acanthite’s presence causes a gradual color-change.

All these changes are also present in pyrargyrite.

Spiritually, what is the meaning of proustite?

Image credit: Rob Lavinsky, iRocks.com – CC-BY-SA-3.0

Proustite Meaning & History

Proustite symbolizes strength, courage, and resilience. It can also represent intuition, self-awareness, and spiritual awakening.

Early History

French mineralogist and geologist François Sulpice Beudant named proustite in 1832 after French chemist Joseph L. Proust, who first identified and proved proustite as a distinct mineral from pyrargyrite.

Proustite’s type locality is Jáchymov in the Czech Republic, formerly called Sankt Joachimsthal or Joachimsthal until 1945. The town has a rich silver mining history.

Established in 1516, it became the second most populous town in Bohemia after Prague because of the abundance of silver.

Some silver mined there was minted into Joachimsthaler coins starting in 1520. The shortened form, thaler, eventually inspired the dollar.

Chile Discovery

Chilean farmer and miner Juan Godoy stumbled upon silver deposits in Chañarcillo, Chile, in 1832, kickstarting the Chilean silver rush.

Miners eventually found proustite and nicknamed it sangre de torro, meaning “blood of the bull,” as its host rock was “bleeding” with the silver ore.

Proustite Healing Properties

As a popular red healing stone, proustite has the energizing and motivating properties of other red gemstones, along with being an effective root chakra stone.

Physical Healing

Proustite’s metaphysical properties are said to include treating physical problems related to:

• Prostate

• Circulation

• Infections

• Kidney & bladder

• Menopause

Emotional Healing

Emotionally, proustite is said to bring courage and insight into your true purpose. It may also attract abundance, facilitate inner peace, and provide emotional balance.

Image credit: Maurizio Dini, CC-BY-SA-3.0

Proustite Gemstone Properties

Besides rarity, proustite gem value depends on color, cut, clarity, transparency, and carat weight affect their value.

Color

Proustite colors are on the bright to deep red spectrum, sometimes with yellow or purple undertones. Specimens that have deteriorated (either from light exposure or time) are often black and not as valuable.

The cause of proustite’s color falls into the band theory of color origins, as it’s caused by medium band-gap semiconductors.

Cut

The stone’s rarity and softness make faceted proustites scarce. Most have rectangular step, round, or octagon shapes.

Most proustite for sale is available as rough (uncut) specimens.

Clarity & Transparency

Clarity, the degree of visible inclusions in a gem, can affect a stone’s transparency and value. Some proustites have internal fractures or growth zoning.

Inclusions are only visible in transparent specimens, however, which are already rare enough to be valuable regardless of clarity.

Carat Weight

Although proustite crystals currently in collections or displays could yield huge faceted gems, they probably won’t be cut any time soon. Some particularly large faceted proustites have been 10 to 12 carats.

Synthetics

Synthetic proustites are not only used in research but may also pop up as faceted stones in collections.

Image credit: Rob Lavinsky, iRocks.com – CC-BY-SA-3.0

Proustite Formation & Sources

Proustite forms in hydrothermal deposits as a low-temperature, late-phase mineral. It’s usually found in the oxidized zone (above the water table) or supergene zone (close to the surface).

Supergene mineral formation involves precipitation water going down into the ground, oxidizing primary sulfide minerals while forming sulfuric acid and oxidized metal solutions. These solutions travel further down into the oxidized zone where they can further react with primary minerals to create secondary minerals like proustite.

Geographically, where is proustite found?

Mining Locations

The best proustite crystals, and most facetable material, from Chile, especially Chañarcillo. The Czech Republic also remains a top source.

Other significant sources include:

• Canada

• Germany

• France

• Italy

• Mexico

• Peru

• USA (California, Colorado, Idaho, Nevada)

Image credit: Rob Lavinsky, iRocks.com – CC-BY-SA-3.0

Proustite Price & Value

Proustite is rare as a mineral and gemstone, so its prices generally reflect that. However, faceted proustite gems are the priciest.

Faceted proustites range from around $200 to $1,200 per carat or about $700 to $1,900.

Specimens with red coloring cost more than those with only gray to black coloring.

Overall, gray specimens are usually around $30 to $90, while red specimens are about $150 to $700 or higher. The highest-quality collector specimens range from $2,500 to almost $10,800 each.

Proustite Care and Maintenance

First, it’s important to note that proustite contains arsenic, which is toxic if ingested. We have safety tips on handling toxic minerals, but the biggest tips here are:

1. Wear proper safety equipment if cutting or polishing proustite to avoid inhaling any proustite dust or fumes.

2. Wear gloves to handle proustite and dispose of the gloves afterwards or keep them in a designated box to avoid cross-contamination.

3. Keep the stone away from anyone who might put it in their mouth (e.g. children and pets).

4. Do not use proustite to make elixirs.

Proustite scratches easily, increasing the risk of it releasing arsenic-containing fibers. We recommend only keeping proustite in an enclosed display case.

In terms of gemstone care, it’s best to keep proustite in darkness (at a cool temperature) to maintain its transparency and coloring. Although many prostitutes will inevitably darken over time regardless, light exposure and heat quicken the process.

Wearing gloves, you can clean proustite with mild soap, water, and a soft microfiber cloth.

On the Prowl for Proustite?

Despite the number of minerals containing silver, all of them are rare. Proustite may seem like a scary mineral, but with the proper care, this gorgeous rarity is a dream for any collector.

Buy proustite and more gemstones today!