Hydrogrossular Garnet Gem: Traits, Meaning, Prices & More

Hydrogrossular garnet is a translucent to opaque gemstone considered by most gemologists to be a variety of the grossular garnet species. It’s largely known for being used as a green jade substitute, though it comes in other colors.

Is hydrogrossular garnet rare? As a mineral, hydrogrossular garnet isn’t very rare. This variety is the only garnet to be almost exclusively translucent to opaque — fully transparent hydrogrossular stones are extremely rare. As such, these garnets aren’t faceted as often as other varieties.

Today, we’ll go over all of hydrogrossular garnet’s mineral and gemstone properties, along with this gem’s prices, history, meanings, and more!

What Is A Hydrogrossular Garnet?

Hydrogrossular garnet is a commonly green, pink, or white semi-precious gemstone usually classified in the grossular garnet species.

As a garnet, this gem is a January birthstone, lucky Capricorn or Aquarius stone, and 2nd wedding anniversary gem.

Sometimes, hydrogrossular garnet is called “hydrogarnet.”. New Zealand specimens may be called “rodingite.”

Most often, hydrogrossular garnets have trade names related to their resemblance to jade, such as:

• Transvaal Jade

• African Jade

• South African Jade

• Garnet Jade

All of these terms are misnomers, since hydrogrossular garnet is not related to jadeite or nephrite, the two types of jade. But the nicknames are often used for hydrogrossular stones — sometimes intermixed with zoisite — from the Transvaal region of South Africa.

A mineral more similar to hydrogrossular garnet is idocrase (vesuvianite) --- pictured below --- which is another common jadeite simulant. Many stones contain both hydrogrossular garnet and idocrase.

The two minerals have similar density, refractive indices, magnetism, transparencies, and colors. In fact, many near-transparent green “hydrogrossular garnet” gems are actually idocrase.

So, how do you identify a hydrogrossular garnet? Distinguishing hydrogrossular garnet from idocrase requires advanced professional testing, but identifying hydrogrossular stones in general starts with getting familiar with their mineral traits.

Hydrogrossular garnet has been studied for geological research into its elastic properties and formation (as a water-bearing mineral) in Earth’s upper mantle. Scientists have also synthesized hydrous garnets for research.

Pictured above: Faceted idocrase

Hydrogrossular Garnet Specifications & Characteristics

The garnet gemstone family has two primary, overarching series: pyralspite and ugrandite. Pyralspite contains the species pyrope, almandine, and spessartite. Ugrandite contains uvarovite, grossular, and andradite.

Mantle-derived pyralspite garnets have been found with 0.005 to 0.01 percent (5 to 100 ppm) water, while mantle-derived ugrandites can have up to 20 percent water.

Some consider hydrogrossular an entirely distinct mineral species that’s similar to but separate from garnets. However, most gemologists consider hydrogrossular garnets a variety of the calcium aluminum silicate species grossular but with hydroxide partially replacing silica.

The hydrogrossular garnet formula is written as Ca3Al2(SiO4)3-x(OH)4x or Ca3Al2(SiO4)3-x(H4O4)x.

Distinct hydrogrossular crystals are rare — instead, the mineral usually occurs as dense, microcrystalline masses. Some massive specimens are actually grossular, though, not hydrogrossular.

Hydrogrossular garnet properties listed:

• Mohs hardness: 6.5-7.5

• Color: Green, blue-green, pink, white, gray, brown; Sometimes rose-red or yellow; Can be multi-colored

• Crystal structure: Isometric (cubic)

• Luster: Waxy, vitreous, or sub-adamantine

• Transparency: Translucent to opaque

• Refractive index: 1.67-1.814; Usually 1.72

• Density: 3.13-4.20

• Cleavage: None

• Fracture: Conchoidal or splintery

• Streak: White

• Luminescence: Usually none; Sometimes fluorescence - pink or pinkish-orange in green or pink specimens

• Pleochroism: None

• Birefringence: None

• Dispersion: None

Pictured above: Hydrogrossular garnet specimen with black chromitite bands, sold as "Transvaal jade" | Image credit: James St. John, Flickr, CC-BY-SA-2.0

Types of Hydrogrossular Garnet

Technically, hydrogrossular garnet can be considered a series, with formulas varying based on how much silica (SiO4) is substituted by hydroxide or water (H4O4 or H2O), or “hydration degree.” The series goes from:

• Grossular: Little to no substitution - 0 to 0.2 degrees

• Hibschite: Some substitution - 0.2 to 1.5 degrees (over 50 percent grossular)

• Katoite: More substitution - 1.5 to 3 degrees (under 50 percent grossular)

We should note that the International Mineralogical Association (IMA) doesn’t consider hibschite an official species — this name is informal.

However, hydrous content may vary among different hydrogrossular garnets. Impurities like chromium and/or vanadium along with less hydrous content (water or hydroxide) may be the reason dark green hydrogrossular garnets usually have higher refractive indices than lighter green ones.

Refractive indices also lower from the grossular end to the katoite end.

On the spiritual side, what is the meaning of hydrogrossular stones?

Hydrogrossular Garnet Meaning & History

Hydrogrossular garnets carry many of grossular garnet’s meanings, symbolizing abundance, success, and gratitude. Green hydrogrossular garnets specifically represent rebirth, hope, and growth.

Like all garnets, hydrogrossular crystals are associated with the Egyptian goddess of war and healing, Sekhmet. Green garnets like this one also honor the Greek goddess of spring and reincarnation, Persephone.

History

Compared to most garnet varieties, hydrogrossular garnet’s history is much more recent, occurring over the last century. The first discovery was technically in 1908, when English-South African geologist Arthur Lewis Hall found specimens in the Transvaal of South Africa.

However, Hall misidentified the minerals as massive grossular (chromian lime) garnet with significant water content. These hydrogrossular stones later gained the nickname “South African jade.”

The stone was first officially identified and named in 1943 by Colin Osborne Hutton, New Zealand-born mineralogy professor at Stanford University.

His analysis of the material, found in rodingites from the Nelson-Dun Mountain area of New Zealand, was described in his article “Hydrogrossular, a new mineral of the garnet-hydrogarnet series” published in Transactions And Proceedings of The Royal Society of New Zealand.

Hutton named the garnet for its hydroxide and water content.

In 1960, Hutton would also name and co-write the first description of papagoite.

Hydrogrossular Garnet Healing Properties

As popularly green healing stones, hydrogrossular garnets have the calming and joyful properties of other green gemstones. They’re also great heart chakra stones.

Physical Healing

Physically, hydrogrossular garnets are said to treat issues related to:

• Arthritis

• Blood circulation

• Immune system

• Inflammation

• Metabolism

• Vitamin A absorption

Emotionally, what are the benefits of hydrogrossular garnets?

Emotional Healing

Crystal healers recommend hydrogrossular garnets for:

• Attracting abundance

• Boosting creativity

• Encouraging love & acceptance

• Inspiring harmonious collaboration

• Reducing anxiety

• Supporting personal growth

They definitely have metaphysical value, but what about regular gemstone value?

Hydrogrossular Garnet Gemstone Properties

Like most garnets and gems overall, hydrogrossular garnet value depends on color, cut,

Color

Hydrogrossular garnet colors include blue-green, green, pink, white, and gray. Some yellow and honey brown specimens have been found, but they’re rare.

As a jade simulant, the most popular hydrogrossular colors are green to blue-green, with high value going to vibrant shades like apple green.

Some hydrogrossular garnets are multi-colored, with combinations like pink, green, and white (dubbed “watermelon garnet”) or white, gray, and green, to name a couple variations. Many specimens have black pepper-like speckling.

Impurities behind some hydrogrossular garnet’s colors include:

• Green: Chromium, vanadium, and/or iron

• Pink: Manganese

• Colorless: Little to none

Cut

Although most garnet varieties are commonly faceted, hydrogrossular garnets are faceted less often. Usually, hydrogrossular gems are cut into cabochons, beads, or carvings.

Carvings are popular both to imitate jade and to take advantage of hydrogrossular garnet’s mid-range hardness. Common shapes are towers, points, skulls, spheres, and pyramids.

Clarity & Transparency

Grossular garnets have Type II clarity, so minor visible inclusions are expected. Fewer inclusions usually means higher transparency and value.

Hydrogrossular garnets often have dark, pepper-like inclusions, which may be:

• Magnetite

• Chromite

• Diopside

Fully transparent hydrogrossular garnets are extremely rare. Many translucent specimens have cloudy patterns, with sections of varying translucence — possibly due to water content.

Carat Weight & Size

Massive hydrogrossular garnets can be quite large, yielding big cabochons and carvings. Most faceted stones are smaller.

Pictured above: A pink hydrogrossular cabochon with the rough stone slab from which the shaped piece was severed | Image credit: R.H.C. Langendam, CC-BY-SA-3.0

Hydrogrossular Garnet Formation & Sources

Unlike most garnets, hydrogrossular stones usually form in massive habits, meaning aggregates of many microcrystalline crystals (like chalcedony) formed together when the environment didn’t have all the factors present long enough for individual gemstone formation.

The hydroxide and/or water content may come from forming in hydrated eclogitic layers of Earth’s upper mantle.

Hydrogrossular garnets are also characteristic of rodingites, formerly igneous rocks chemically altered by fluids after serpentinization.

Geographically, where does hydrogrossular garnet come from?

Mining Locations

The main sources of hydrogrossular gem material are:

• Canada

• China

• Myanmar

• South Africa

• USA

• Zambia

Hydrogrossular Garnet Price & Value

Luckily, hydrogrossular garnets are more affordable than other types of garnets, especially popular green garnets like tsavorite or demantoid.

Faceted hydrogrossular garnet gems range from around $5 to $60 per carat, or about $40 to $550 total, with higher prices for rarer colors or greater translucence.

Hydrogrossular cabochons have a wider range, from about $0.50 to $70 per carat or about $10 to $410. Higher prices usually go to cabochons with greater coloring, translucence, and size.

General price ranges for hydrogrossular garnet jewelry are:

• Rings: $40 to $800

• Beaded Bracelets: $15 to $80

• Beaded Necklaces: $40 to $80

• Earrings: $30 to $80

• Pendants: $35 to $720

For carvings, prices vary from around $10 to $240, increasing for larger, more intricate pieces.

Rough hydrogrossular garnet specimens cost about $0.04 to $0.30 per carat or $30 to $1,050 total.

Hydrogrossular Garnet Care and Maintenance

Last up: gemstone care. Given their mid-range hardness, hydrogrossular garnet jewelry should have protective settings, particularly rings.

Keep the stone away from extreme heat or it will fracture. It also reacts to hydrofluoric acid.

You can clean hydrogrossular garnet with mechanical systems (e.g. ultrasonic or steam), but the safest method is warm, soapy water and a soft toothbrush.

Hypnotized by Hydrogrossular Garnet?

Hydrogrossular garnet is a truly unique garnet and gemstone overall. It’s much more than just a jade substitute — this stone has wonderful colors, decor options, and rarity to boot!

Buy hydrogrossular garnet gemstones today!