Pumpellyite Gemstone: Properties, Meanings, Value & More

Pumpellyite (pronounced puhm-PELL-ee-eyet) is the name of a group of minerals or one of the minerals in that group. The most well-known pumpellyite variety is called chlorastrolite, which is also the Michigan state gemstone.

The mineral forms are fairly common, though some pumpellyite varieties are rarer than others. Gem-quality pumpellyite stones are rare, especially in large sizes.

Pumpellyite is mostly known among collectors, but beautiful chlorastrolite gems appear more often in jewelry.

In this guide, you’ll learn all the different types of pumpellyite, along with the stone’s history, characteristics, prices, and benefits.

Pictured above: Polished chlorastrolite (pumpellyite variety) from Isle Royale National Park, Michigan, USA | Image credit: A. E. Seaman Mineral Museum

What Is A Pumpellyite?

“Pumpellyite” is used for a group of stones or one of the semi-precious gemstones in that group. Another name for this group is “lotrite,” though “lotrite” is also sometimes used as a moniker for chlorastrolite.

Besides lotrite, chlorastrolite has a few other nicknames, including:

• Isle Royale Greenstone

• Green Turtle Stone

• Greenstone / Michigan Greenstone

• Green Starstone

• Lake Superior Greenstone

• Keasargeite

• Zonochlorite (also used for magnesium-bearing pumpellyite; misnomer)

• Lintonite

• Uigite (variety from Uig, Scotland)

Some of these nicknames reflect chlorastrolite’s appearance — usually a green and white pattern resembling a tortoise shell — or where it’s found (more on that in the History and Mining Locations sections later).

We should note that the name “greenstone” is also used for:

• Various green minerals and rocks used in ancient jewelry and ornamental items

• Durable green stones, usually nephrite jade and the translucent serpentine variety bowenite, from New Zealand; Also called “New Zealand jade” and Pounamu (a Māori word)

• Forms of green jade (nephrite or jadeite) from various localities

Given its similarities to jade, pumpellyite can substitute as an alternative March birthstone or Pisces stone.

Astrologically, pumpellyite is a Leo birthstone.

Pumpellyite Specifications & Characteristics

As you know, pumpellyite is a group of minerals. More specifically, there are two groups: the “pumpellyite group” and “pumpellyite subgroup.”

The larger pumpellyite group encompasses hydrous calcium silicates with the general formula Ca2XZ2[Si2O6(OH)][SiO4](OH)2A. In the formula, X can be magnesium, ferrous/ferric iron, aluminum, manganese, or vanadium, and Z can be aluminum, ferrous iron, manganese, vanadium, or chromium. The A position can be hydroxide or oxygen.

This group includes okhotskite, poppite, the julgodite subgroup, the shuiskite subgroup, and the pumpellyite subgroup.

The pumpellyite subgroup contains 5 minerals, and the formula for pumpellyite slightly varies with each pumpellyite mineral — more on these in the next section.

Pumpellyite minerals can be fibrous (in dense mats or masses), lamellar masses (layers of thin plates), amygdaloidal, or fracture fillings.

Pumpellyite Mineral Properties:

• Mohs hardness: 5 to 5.5; Chlorastrolite 5-6 from other minerals intermixed

• Color: Usually shades of green including olive, blue-green, blackish-green, and emerald-green; Can be brown, white, blue, light gray, or pinkish-brown

• Crystal structure: Monoclinic

• Luster: Vitreous or dull; Silky when fibrous

• Transparency: Usually translucent; Mg-bearing - translucent to opaque; Al-bearing - transparent to translucent

• Refractive index: 1.674-1.800; Ranges vary by mineral, highest is manganese-bearing (1.752-1.800)

• Density: 3.18-3.41; Varies by mineral, highest is aluminum-bearing (3.41); Chlorastrolite 3.1-3.5 from other minerals intermixed

• Cleavage: Usually distinct/good on {001} & {100}; None in massive material; Manganese-bearing - presumably perfect on {001}; Aluminum-bearing - perfect on {100}

• Fracture: Uneven/irregular or splintery

• Streak: White; Manganese-bearing - light grayish-pink

• Luminescence: None

• Pleochroism: Present & strong, colors vary by mineral; a - Colorless or light greenish-yellow or light yellow or light pink; β - Blue-green or light green or deep grass-green or brownish-yellow; γ - Colorless or light yellowish-brown or brownish-yellow or brownish-pink

• Birefringence: 0.013-0.048; Ranges vary by mineral, highest is manganese-bearing (0.048)

• Dispersion: Weak to relatively strong; Lower in pale-colored specimens

• Optical effects: Chatoyancy (chlorastrolite)

Pictured above: Pumpellyite-(Mn) | Image credit: D. Nishio-Hamane, Flickr, CC-BY-SA-2.0

Types of Pumpellyite

The pumpellyite subgroup contains 5 minerals:

• Pumpellyite-(Mg): Magnesium-bearing; Formula Ca2MgAl2[Si2O6OH][SiO4](OH)2(OH); Green, blue, blackish-green, or brown

• Pumpellyite-(Fe2+): Ferrous iron-bearing; Formula Ca2Fe2+Al2[Si2O6OH][SiO4](OH)2(OH); Greenish-black

• Pumpellyite-(Fe3+): Ferric iron-bearing; Formula Ca2Fe3+Al2[Si2O6OH][SiO4](OH)2O; Greenish-black

• Pumpellyite-(Mn2+): Manganese-bearing; Formula Ca2Mn2+Al2[Si2O6OH][SiO4](OH)2(OH); LIght gray or pinkish-brown

• Pumpellyite-(Al): Aluminum-bearing; May contain more magnesium than pumpellyite-(Mg); Formula Ca2AlAl2[Si2O6OH][SiO4](OH)2O; Emerald-green to white, sometimes blue undertones

Both pumpellyite-(Fe2+) and pumpellyite-(Fe3+) may be called “ferropumpellyite.” Specimens that contain both ferrous and ferric iron may be called “julgolditet.”

Chlorastrolite is a type of pumpellyite-(Mg). It usually forms in dense fibrous aggregates, often with other minerals intermixed. When the fibers occur in radial clusters, it produces the signature tortoise-shell or turtle-back pattern and a form of chatoyancy.

Pictured above: Chunk of chlorastrolite specimen found in Keweenaw Peninsula | Image credit: Charles Dawley, Flickr, CC-BY-SA-2.0

Pumpellyite History

The first pumpellyite was discovered in the Keweenaw Peninsula of Michigan, USA in the 1920s.

American geologist Dr. Alfred Wandke first identified pumpellyite as a new mineral, describing it as “green zoisite.”

In their 1925 description, American mineralogists Charles Palache and Helen E. Vassar named the mineral pumpellyite after Raphael Pumpelly, a geologist who pioneered the study of that region’s minerals.

Discovery of Each Pumpellyite Mineral

In 1973, the International Mineralogical Association (IMA) added suffixes for the pumpellyite minerals to indicate the unique element in each one’s formula.

Listed by order of their discovery:

1. Pumpellyite-(Mg): Described in 1925 by Charles Palache & Helen E. Vassar; Discovered in Michigan, USA

2. Pumpellyite-(Fe2+): Described in 1965 by V.V. Zolotukhin, Yu.R. Vasil'ev, & N.I. Zyuzin; Discovered in Krasnoyarsk Krai, Russia (Siberia)

3. Pumpellyite-(Fe3+): Described in 1973 by Elio Passaglia; Discovered in Bulla, Italy

4. Pumpellyite-(Mn2+): Described in 1981 by Satoshi Matsubara, Akira Kato, & Ryoichi Yamamoto; Discovered in Minami-Alps, Japan

5. Pumpellyite-(Al): Described in 2005 by Frédéric Hatert & Thomas Theye; Discovered in Bertrix, Belgium

Chlorastrolite History

American geologist Josiah D. Whitney and scientist Charles T. Jackson first discovered chlorastrolite in Isle Royale at Lake Superior, Michigan, in 1847 — before pumpellyite!

It’s named from the Greek terms chloros, meaning “green,” and astros, meaning “star,” or “green star stone.”

Chlorastrolite was later found in the Carpathian Mountains of Europe, described by Murgoci in 1901 with the name “lotrite.”

Some thought it was a variety of thomsonite or prehnite. It wasn’t until the 1940s that W.B. Griffiths identified it as a pumpellyite variety.

Pumpellyite Gemstone Healing Properties

As a commonly green healing stone, pumpellyite’s meaning reflects that of other green gemstones, representing hope and renewal. It's also used as a heart chakra stone.

Physical Healing

Physically, pumpellyite gemstone benefits are believed to help with:

• Motion sickness

• Muscle fatigue

• Toxin buildup

Emotional Healing

Emotionally, pumpellyite is said to:

• Lower anxiety

• Ease difficult transitions

• Promote positivity

• Alleviate anger

Pictured above: Enlargement of polished chlorastrolite (pumpellyite variety) cabochon | Image credit: Michigan.gov document

Pumpellyite Gemstone Properties

Besides rarity, pumpellyite gemstone value depends on color, cut, clarity, transparency, and carat weight.

Color

Most pumpellyite stones come in some shade of green, but some are brown, blue, gray, pinkish-brown, or white. Darker colors have higher birefringence, dispersion (fire), and refractive indices.

The best pumpellyite color is intense emerald-green.

Chlorastrolite can be pink, green, blue-green, black, or a combination of these. Green colors in chlorastrolite are caused by ferrous iron impurities and the charge transfer of ferrous iron to ferric iron. Intense, visible patterns command higher prices.

Cut

Because gem-quality pumpellyite is rare, any cut pumpellyite gems are inherently valuable. Most faceted pumpellyite stones are pumpellyite-(Mn) or layered with osumilite.

Chlorastrolite stones are often cut into cabochons.

Clarity & Transparency

Clarity describes the degree of visible inclusions in a stone, which lowers its transparency and value.

Higher translucence in pumpellyite can also raise value, as transparency is rare. Pumpellyite is often found intergrown with other minerals like epidote, prehnite, or zeolite.

Carat Weight & Size

Faceted pumpellyites are small, always under 2 cts. High-quality chlorastrolite gems are also small, rarely over 0.5 inch (1.27 cm). Most chlorastrolite cabochons are 1 to 2 inches long and under 2 grams (10 cts).

Pictured above: Blue prehnite where some of the "balls" are green, but a few of them show a rare seen blue hue which is caused by underlying dark pumpellyite; Richard Kosnar Collection | Image credit: Rob Lavinsky, iRocks.com – CC-BY-SA-3.0

Pumpellyite Formation & Sources

Most pumpellyite minerals form during low-grade metamorphism. They’re usually found in metamorphosed basalts and gabbros.

What type of metamorphism is prehnite pumpellyite? Prehnite-pumpellyite facies represent a metamorphic grade from 250-350°C and 1-7 kb of pressure.

What minerals are in prehnite-pumpellyite facies? It depends on the rock that underwent metamorphism. Most often, minerals in these facies (besides prehnite and pumpellyite) include:

• Actinolite

• Albite

• Chlorite

• Muscovite

• Quartz

Mining Locations

Where is pumpellyite found? Michigan is the only known source for gem-quality chlorastrolite.

Pumpellyite is mainly found in:

• Austria

• Finland

• New Zealand

• Scotland

• South Africa

• USA (California, New Jersey)

• USSR

Pictured above: Chlorastrolite parcel from Isle Royale National Park, Lake Superior, Keweenaw Co., Michigan | Image credit: Grand Rapids Public Museum

Pumpellyite Gemstone Price & Value

Faceted pumpellyite gemstones cost around $30-$80 per carat or about $20-$90 each.

Chlorastrolite cabochons go for around $2.50-$35 per carat or $25-$160 each.

Rough pumpellyite for sale ranges from about $3-$175, but most are under $0.50-$1 per carat.

Tumbled chlorastrolite stones go for around $3-$11 each.

Chlorastrolite jewelry prices have these general ranges:

• Rings: $140 to $2,000

• Cuff Bracelets: $750 to $1,600

• Pendants: $170 to $1,100

• Earrings: $45 to $500

Last up: gemstone care.

Pumpellyite Care and Maintenance

We recommend protective settings on chlorastrolite jewelry, particularly rings.

Keep pumpellyite away from sulfuric or hydrofluoric acid.

Clean pumpellyite with warm water, mild soap, and a soft toothbrush.

Are You Pumped Up for Pumpellyite?

Whether you’re a Michigan native or not, pumpellyite is a beautiful and diverse stone to celebrate. With plenty of varieties, including the most popular chlorastrolite, you’re bound to find a pumpellyite gem that suits you!

Buy pumpellyite and other rare gemstones today!