Bayldonite Gemstone: Properties, Meanings, Value & More

Bayldonite is a lesser-known mineral usually found in shades of green and first discovered in England, UK. The stone is mostly known among collectors of unusual stones.

In terms of rarity, bayldonite is a rare mineral and even rarer gemstone. Some lapidarists (gem cutters) will cut bayldonite cabochons, which can even look metallic sometimes, but the stone isn’t usually cut.

Our Gem Rock Auctions experts love rare, lesser-known minerals, so we’re excited to teach you all about bayldonite’s value, history, properties, and uses!

As bayldonite contains arsenic, we’ll also explain important tips for handling the mineral safely.

Pictured above: Radiating spray of grass-green bayldonite that completely replaced a mimetite cluster, dated 1890s-1910s; Sussman and Dr. Georg Gebhard Collections; Image credit: Rob Lavinsky, iRocks.com – CC-BY-SA-3.0

About Bayldonite Stone

Bayldonite (pronounced BAIL-done-ite) is a rare semi-precious gemstone known in various shades of green or yellow-green. Other monikers for bayldonite are cuproplumbite and parabayldonite.

Somewhat similarly, bayldonite mixed with duftite-α was once (erroneously) called “arsentsumebite.”

French chemist and mineralogist Jean Claude Guillemin reported on making the first synthetic bayldonite in 1956.

He mixed hydrated sodium hydrogen arsenate with lead(II) acetate trihydrate and copper(II) nitrate trihydrate, boiled the mixture, then cooled it. Lastly, he filtered, rinsed, and air-dried it. The result was a solid containing both bayldonite and schultenite.

Spiritually, bayldonite is associated with resilience, personal growth, and regeneration.

Astrologists generally recommend green gemstones like bayldonite for those born under Taurus.

Bayldonite Specifications & Characteristics

Bayldonite is a copper lead arsenate. Its formula may be written as:

• (Pb,Cu)3(AsO4)2(OH)2

• PbCu3(AsO4)2(OH)2

• Cu3PbO(AsO3OH)2(OH)2

The last formula is the one approved by the International Mineralogical Association (IMA).

In terms of habits, bayldonite crystals may be tabular or fibrous and radiating. When twinned, crystals form pseudo-scalenohedral trillings — three intergrown crystals making a hexagonal shape (trillings) that appear similar to a scalenohedron, a bipyramid with zig-zag middle edges (pseudo-scalenohedral) — on the (311) composition plane.

Bayldonite crystals are rare, though. More often, it occurs as fibrous mammillary (rounded with knobby surface), granular, or massive crusts.

Here are bayldonite’s properties listed:

• Mohs hardness: 4.5

• Color: Green, apple-green, grass-green, yellow-green, dark green, blackish-green, or black

• Crystal structure: Monoclinic

• Luster: Resinous, waxy, or greasy; Near-metallic in some cabochons

• Transparency: Transparent to translucent (crystals); Opaque (masses)

• Refractive index: 1.951-1.991

• Density: 5.24-5.65

• Cleavage: None

• Fracture: Conchoidal or irregular/uneven

• Streak: Siskin green (warm, muted yellowish-green) to apple green

• Luminescence: None

• Pleochroism: None

• Birefringence: 0.040

• Dispersion: Strong

Pictured above: Large specimen of bayldonite in three different forms: massive bayldonite, layer of bayldonite druzy, and acicular bayldonite crystals in central vug; Dated early 1900s from Namibia; George Elling Collection | Image credit: Rob Lavinsky, iRocks.com – CC-BY-SA-3.0

Bayldonite History

British chemist Sir Arthur Herbert Church wrote the first official description of bayldonite in 1865 based on specimens from Cornwall, England, UK.

Church is also known for discovering the red pigment turacin and being an expert on paint chemistry (which he applied to preserving artwork at the Palace of Westminster), pottery, and agricultural chemistry.

Church named it after English physician Dr. John Bayldon, his “friend and former colleague” who was also known for his work in botany and medicine.

Although some claim Bayldon found the first bayldonite specimens, English mineral dealer Richard Talling actually gave Church the first specimens. Talling has been nicknamed “the greatest Cornish dealer of all time.”

Church described the new mineral as a “hydrous cerous phosphate” — “cerous” meaning containing cerium. The original specimens were “grass-green to blackish-green” occurring “in minute mammillary concretions, having a drusy surface” according to Church’s description.

Before Church’s description, German mineralogist Friedrich Karl Biehl described similar minerals from Namibia in 1919, 1921, and 1925. He called the minerals “parabayldonite” or “cuproplumbite.”

The type locality of bayldonite, presumably where it was first discovered, is the Penberthy Croft Mine in Cornwall, England, UK. However, Talling’s specimens only listed them as from “Cornwall,” so it’s unclear if this mine was the exact locality.

Bayldonite Healing Properties

As a green healing stone, bayldonite has the rejuvenating and uplifting properties of other green gemstones. It’s also used as a solar plexus or heart chakra stone.

According to crystal healers, other bayldonite benefits include:

• Balancing emotions

• Encouraging empathy

• Stimulating mental clarity

• Getting you more in tune with nature

• Dispelling negativity

• Increasing resilience

• Facilitating creative expression

Warning: Don’t drink any elixirs containing bayldonite and don’t sleep with bayldonite in your bed. (More on handling bayldonite safely in the Care and Maintenance section.)

Pictured above: Jack-straw cluster of green bayldonite formed after long, thin, mimetite crystals | Image credit: Rob Lavinsky, iRocks.com – CC-BY-SA-3.0

Bayldonite Gemstone Properties

Given the rarity of cut gemstones, bayldonite’s value isn’t graded with standard criteria. We’ll still go over how the usual factors may apply to bayldonite:

• Color: Displaying various shades of yellow to green, bayldonite is generally most valuable in brightly saturated uniform greens like apple-green or grass-green.

• Cut: Only fibrous masses from Namibia can be cut into cabochons. Almost all bayldonite for sale is rough (uncut).

• Transparency: Crystals are already rare, so fully transparent bayldonite crystals could command high prices.

• Luster: Specimens with shinier luster (resinous) may be more valuable than greasy or waxy specimens. Rare near-metallic cabochons may also be valuable.

Before it's sold, how does bayldonite form?

Pictured above: Rare, old-time Namibian specimen with blue azurite crystals on moss-colored botryoidal bayldonite with coated botryoidal malachite | Image credit: Rob Lavinsky, iRocks.com – CC-BY-SA-3.0

Bayldonite Formation & Sources

Bayldonite forms as a secondary mineral, meaning primary minerals (e.g. mimetite) undergo alteration and transform into bayldonite.

The mineral is found in oxidized zones of lead-copper deposits.

Commonly associated minerals include:

• Anglesite

• Azurite

• Barite

• Beudantite

• Cerussite

• Cuprian Adamite

• Duftite

• Keyite

• Malachite

• Mimetite

• Olivenite

• Philipsbornite

• Quartz

• Schultenite

• Tsumebite

Geographically, where is bayldonite found?

Mining Locations

The only occurrence of bayldonite in sizable quantities is in Tsumeb, Namibia.

The mineral is also found in:

• Australia

• France

• Ireland

• Kazakhstan

• UK (England)

• USA (Arizona, Montana, Nevada)

Pictured above: Glassy, cyclically-timed cerussite crystals scattered on matrix covered with mounded, botryoidal, green bayldonite; George Elling Collection | Image credit: Rob Lavinsky, iRocks.com – CC-BY-SA-3.0

Bayldonite Price & Value

Since bayldonite cabochons are generally only cut by collectors or enthusiasts, the bayldonite you’ll find for sale is always rough.

Prices vary broadly for bayldonite rough.

At the high end, you have large, vibrant specimens like apple-green bayldonite crystals attached to other rare minerals like wulfenite, dioptase, or mimetite. These go for around $200 to over $2,000.

In the middle are smaller but still vibrant specimens, like lime-green bayldonite crystals, often on calcite. These go for $40 to $175.

The more affordable specimens are generally small specimens with bayldonite coatings, which are $15 to $30.

Bayldonite Care and Maintenance

Before we discuss keeping your mineral safe, your safety comes first. Bayldonite contains lead, copper, and most notably, arsenic.

Above all, avoid ingestion. Since bayldonite is relatively soft, it can be easily scratched, meaning arsenic-containing particles. Here are some of our safety tips for handling a hazardous mineral like bayldonite:

1. Wear protective gear if cutting or polishing the stone.

2. Thoroughly wash your hands after handling the mineral.

3. Don’t lick the mineral, and store it away from anyone who might, like pets or children.

4. Don’t wear bayldonite in jewelry.

If you’re not a lapidarist working with bayldonite, just be sure to wash your hands after handling the stone.

Onto gemstone care, bayldonite’s relatively low Mohs hardness and brittle tenacity make it fairly fragile. We recommend avoiding washing bayldonite. If it’s dusty, you can gently wipe it down with a dust-free microfiber cloth.

Store bayldonite away from harder minerals that could scratch it. Also keep it away from acids.

Break the Mold with Beautiful Bayldonite!

You may not have heard of bayldonite before, but this stone is an intriguing underdog. With gorgeous green hues, rejuvenating healing benefits, and rarity appeal, bayldonite is a great addition to any collection.

Buy bayldonite and other rare gemstones today!