Ekanite Gemstone: Properties, Meanings, Value & More
Ekanite is a unique, commonly green gemstone mostly known among collectors. It’s a recent discovery, first found in the 1950s.
The stone is unique in being one of the few naturally radioactive gemstones.
Is ekanite rare? Yep. The mineral itself is rare, and gem-quality specimens are even rarer, though some have been faceted. Part of the rarity of gem-quality ekanites is that many of these crystals undergo radioactive decay.
Want to learn more? Stick around to find out all of ekanite’s mineral and gemstone properties, along with all of the history, prices, uses, and safety guidelines you need to know.
Pictured above: Green faceted ekanite, about 0.1g | Image credit: Geni, CC-BY-SA-4.0
About Ekanite Stone
Ekanite (pronounced EH-kuh-nyte) is a rare semi-precious gemstone known for its unique composition and optical effects.
A possible simulant of ekanite is brazilianite, though it has lower density, birefringence, and refractive indices.
Many ekanites are quite similar to kornerupine in color, shape, and other properties. Both stones can display asterism.
Ekanite Uses
As one of the few radioactive gemstones, ekanite’s main uses are for studying the effects of radioactive decay on minerals.
One unique aspect of metamict ekanite (more on that next) is that it doesn’t have radiogenic lead loss or post-growth chemical changes. This high radiation resistance is being studied for research into advanced forms of nuclear waste.
Ekanite Specifications & Characteristics
As a calcium thorium silicate, ekanite’s formula is Ca2ThSi8O20. The elements in ekanite can also include the impurities uranium, iron, lead, aluminum, manganese, and magnesium.
The most common impurities are uranium, lead, and iron. As such, the ekanite mineral formula is sometimes written as (Ca,Fe,Pb)2(Th,U)Si8O20 or (Th,U)(Ca,Fe,Pb)2Si8O20.
The complex thorium and uranium silicate mineral steacyite is related to ekanite. In fact, non-metamict “ekanite” discovered in Canada later turned out to be steacyite.
What does “non-metamict” mean? Non-metamict ekanites haven’t undergone the process of metamictization, so they’re still crystalline.
Metamict minerals contain radioactive elements that have caused metamictization, a gradual decay resulting in structural damage. This damage affects the stone’s crystal structure and properties like birefringence, refractive index, density, hardness, and color.
However, these properties can be restored with heat treatment. Other minerals that can be metamict are monazite, sphene (titanite), low zircon, and microlite.
Non-metamict ekanite specimens can be prismatic, granular, or pyramidal crystals, many of which are striated.
Oddly, ekanite specimens carried by water often have uneven shapes with many cavities and bumps, somewhat resembling moldavite. (Most stones carried by water are naturally polished into round, smooth shapes).
Ekanite properties listed:
Mohs hardness: 4.5-6.5
Color: Colorless, straw-yellow, yellow-green, pale to dark green, pale to dark brown, yellowish-brown, dark red
Crystal structure: Tetragonal; Metamict stones may be amorphous
Luster: Vitreous or greasy
Transparency: Transparent to translucent; Some opaque once heated
Refractive index: 1.595-1.597 (metamict); 1.568-1.580 (non-metamict)
Density: 2.95-3.36
Cleavage: Distinct/good on {101}, indistinct on {001}
Fracture: Uneven/irregular
Streak: White
Luminescence: None
Pleochroism: None
Birefringence: 0.001-0.006, usually 0.012; May be isotropic if metamict
Dispersion: 0.012-0.018 (weak)
Optical effects: Sometimes asterism, chatoyancy, or Tyndall scattering
Let’s elaborate on those optical effects.
Pictured above: Faceted bright green ekanite, 0.6 carats | Image credit: Oak Ridge Associated Universities (ORAU) Museum of Radiation and Radioactivity
Types of Optically Phenomenal Ekanite
Ekanite can display some stunning optical phenomena:
Tyndall Scattering
One of the rarest optical gemstone phenomena, Tyndall scattering is when small suspended particles scatter a beam of light, like seeing dust particles floating in a beam of sunlight.
In gemstones like ekanite, Tyndall scattering happens because of tiny inclusions and usually results in the stone looking cloudy and at certain angles, a new color (often blue). You can also see blue Tyndall scattering in some rose quartz stones.
Chatoyancy
Chatoyancy is when a gemstone displays one or more beams of reflected light on its surface due to thin, parallel inclusions.
The most popular type, sometimes seen in ekanite, is a single ray of reflected light dubbed the “cat’s eye” effect.
Asterism
Asterism is when a gemstone displays a multi-rayed, reflected “star” on its surface. The star can have 4, 6, 8, or even 12 rays. Most star (or “asteriated”) ekanites have 4-ray stars, though some have 6- or 8-ray stars.
In fact, the very first ekanite ever found displayed asterism!
Ekanite History
Who found ekanite first? The first person to discover ekanite was Francis Leo Danvis Ekanayake, a Sri Lankan-British gemologist interested in rare gems.
In 1953, Ekanayake bought two dark green, asteriated cabochons from a market in Colombo, Sri Lanka. He and other colleagues found the stones odd because they had some glass-like properties but mineral-like inclusions.
Soon, the specimens were passed to Basil Anderson at the Laboratory of the London Chamber of Commerce (now Gemmological Association of Great Britain, or Gem-A) for analysis.
Anderson found that the stone’s strange properties were because it contained 28 percent thorium and was metamict. He presented these findings to the European Gemological Conference in Copenhagen in 1955.
In 1961, Anderson co-wrote the stone’s first description with British mineralogists Gordon Frank Claringbull, R.J. Davis, and D.K. Hill. They named it after Ekanayake.
Ekanayake tried to find more ekanites and eventually found the original Sri Lankan source, now ekanite’s type locality: gravel beds in Eheliyagoda along a stream near the Ellawala Ella hills.
When the first description came out in 1961, several ekanite specimens had been found. The description also highlighted that heating the metamict specimens made them recrystallize, gain higher densities, and turn opaque with a putty color.
In 1973, non-metamict ekanite was discovered in Canada, but it was confirmed to be steacyite in 1982. Other non-metamict ekanites have been found.
Ekanite Healing Properties
As a primarily green healing stone, ekanite’s spiritual meaning reflects the rejuvenating properties of other green gemstones. It’s also used as a heart chakra stone.
Other purported ekanite gemstone benefits include:
Protection
Emotional balance
Quicker healing
Manifestation
Just be sure to handle ekanite safely (discussed more in the Gemstone Care section later).
Pictured above: Dark green faceted ekanite gemstone | Image credit: Geni, GFDL CC-BY-SA
Ekanite Gemstone Properties
Besides rarity, ekanite gemstone value depends on color, cut, clarity, transparency, and size.
Color
When pure, ekanite is straw-yellow to colorless. However, most non-metamict ekanites are dark red, amber, or brown from inclusions, with more inclusions causing darker colors.
Metamict ekanite gems are usually shades of green. Vibrant yellow-green or emerald-green, transparent ekanites carry higher value.
Cut
Given the stone’s rarity, particularly in crystalline form, faceted ekanites are scarce and valuable. It’s often faceted into rectangular, emerald, or baguette shapes.
Ekanites with optical effects must be cut as cabochons. Many ekanites for sale are rough (uncut).
Clarity & Transparency
Most ekanites have many visible inclusions. Highly transparent stones (without visible inclusions) are valuable, but optical effects caused by inclusions are also valuable.
Common inclusions in ekanite are:
Large birefringent crystals with radiation halos of tiny dots (probably residual liquid drops from microlite formation or turbid centers from radioactivity)
Zeolitic water
Large hematite
Two-phase inclusions (cavities filled with vesicle & liquid)
Irregular-shaped mica scales
Coarse, angular crystals (possibly zircons)
Tiny spherical bubbles
Pinpoint inclusions (often perpendicular rods & platelets that sometimes create crosses)
The pinpoints may also be two-phase, which usually causes asterism.
Comparatively, most zircons have tiny inclusion clouds that are evenly distributed or concentrated into parallel zones.
Carat Weight & Size
Although rare, faceted ekanites can be fairly large given their somewhat high density, ranging from around 1-10 cts. Huge ekanite rough has been found, and the largest ekanite stone (as of March 2016) is a 498-carat cabochon.
That said, most large ekanite crystals are only 2-3 mm long.
Treatments
Metamict ekanites may be heat-treated to restore their crystalline structure.
Pictured above: Close-up view of ekanite crystal | Image credit: D. Nishio-Hamane, Flickr, CC-BY-SA-2.0
Ekanite Formation & Sources
Ekanite minerals are usually found as water-worn pebbles in gem gravels and placer deposits. They can also be found in ejecta from volcanoes and glacial erratic syenite boulders.
Mining Locations
The top source for ekanites is Sri Lanka. Gem-quality ekanites come from Sri Lanka, Myanmar, and Canada. Canada has produced both metamict and non-metamict ekanites.
Additional significant sources of ekanite include:
Italy
Russia
USA (California)
Pictured above: World's largest ekanite as of March 2016 | Image credit: GeologyIn.com
Ekanite Gemstone Price & Value
Given its rarity, it can sometimes be difficult to find ekanite for sale.
Faceted ekanite gemstone prices per carat ranges from around $30 to $170 per carat or about $90 to $1,500 total.
You can find rough ekanite specimens for around $45 each.
Ekanite Care and Maintenance
You’re probably wondering: is ekanite dangerous? With proper handling and storage, no. But ekanite is classified as a high-risk gemstone due to its lead content and radioactivity.
First, don’t wear ekanite jewelry. Before you handle any ekanite, test its radioactivity with a Geiger counter. Keep it in an enclosed, separate container and check any radon buildup periodically with a radon detector. Follow the guidelines in our safety tips for radioactive gems.
Keep ekanite away from other gems.
Entranced by Ekanite?
Certain properties are rare in gemstones, and ekanite has many of them: Tyndall scattering, metamictization, and radioactive elements. With proper safety precautions, this gem is perfect in any collection!
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