ClassicGems.net

Ekanite

Discovered in 1953;   IMA status:  Valid (IMA approved 1958)

Chemistry

Chemical Formula:

Ca₂ThSi₈O₂₀

Calcium Thorium Silicate

Molecular Weight:

856.87 gm

Composition:

Calcium

9.35 %

Ca

13.09 %

CaO

Thorium

27.08 %

Th

30.81 %

ThO₂

Silicon

26.22 %

Si

56.10 %

SiO₂

Oxygen

37.34 %

O

100.00 %

100.00 %

= TOTAL OXIDE

Classification

Mineral Classification:

Silicates (Germanates)

Strunz 8th Ed. ID:

8/E.10-10

Nickel-Strunz 10th Ed. ID:

9.EA.10

9 : SILICATES (Germanates)
E : Phyllosilicates
A : Single nets of tetrahedra with 4-, 5-, (6-), and 8-membered rings

Related to:

None

Members of Group:

None

Varieties:

None

Synonyms:

None

Crystal Data

Crystallography:

Tetragonal - Trapezohedral (may be metamict - a mineral originally crystalline, eventually amorphous due to radiation damage)

Crystal Habit:

Poorly-formed pyramidal crystals, to 1 cm, as clusters of grains; rounded massive.

Twinning:

None

Physical Properties

Cleavage:

Distinct on [101], indistinct on [001]

Fracture:

Irregular, Uneven

Tenacity:

Brittle

Moh's Hardness:

5.0 - 6.5

Density:

3.28 - 3.32 (g/cm³)

Luminescence:

None

Radioactivity:

Strong; GRapi = 542,060.77 (Gamma Ray American Petroleum Institute Units)

Other:

May be metamict due to radiation.

Optical Properties

Color:

Colorless, Yellow, Light to Dark Green, Brown, Red from inclusions

Transparency:

Transparent to Translucent

Luster:

Vitreous

Refractive Index:

1.590 - 1.596  Uniaxial ( - )

Birefringence:

0.0120

Dispersion:

n/a

Pleochroism:

n/a

Occurances

Geological Setting:

Detrital (Sri Lanka); in a glacial erratic syenitic boulder (Tombstone Mountains, Canada); in volcanic ejecta (Case Collina, Italy).

Common Associations:

Fluorite, Garnet, Quartz, Microcline, Clinopyroxene, Apatite, Sodic Plagioclase, Hematite, Thorogummite, Zircon, Titanite (Tombstone Mountains, Canada); Quartz, Feldspar, Pyroxene (Case Collina, Italy).

Common Impurities:

U, Fe, Pb, Al, Mn, Pb, Mg

Type Locality:

Ehiliyagoda (Ehaliyagoda), Ratnapura, Sabaragamuwa Province, Sri Lanka

Year Discovered:

1953 (IMA approved 1958)

View mineral photos:

Ekanite Mineral Photos and Locations

Unusual Gem Categories

Metamict Gems, Radioactive Gems

More Information

Mindat.org
Webmineral.com

Ekanite is an extemely rare gem. It was discovered in 1953 in the gem gravels at Eheliyagoda, near Ratnapura, Sri Lanka. It is also found at Mt. Sainte Hilaire, Quebec, Canada. Ekanite may be strongly radioactive as defined in 49 CFR 173.403 (greater than 70 Bq/gram) due to the presence of Thorium (Th). Ekanite is found in shades of green and brown.

Ekanite is a strongly radioactive mineral and should be stored away from other gems and minerals that are subject to damage from radioactivity and of course human exposure should be limited.

Ekanite is metamict due to its strong radioactivity. Metamictization is a natural, gradual process of the destruction of the internal crystal structure of a mineral due to radiation present in the mineral or from nearby external radiation. Metamictization eventually leaves the mineral amorphous, or without any internal crystal structure. Once this process is complete the mineral is desctibed as metamict.

Ekanite was named after Mr. F. L. D. Ekanayake of Colombo, Sri Lanka, customs officer and Fellow of the Gemmological Association, who came across two unusual gemstones in the local Colombo gem market in 1953. Initially, the stones were suspected to be a devitrified antique glass but Mr. Ekanayake was convinced the material represented a new gem variety and mineral species. It was determined that the raw material came from a gravel pit at Ehiliyagoda (Ehaliyagoda), Ratnapura, Sabaragamuwa Province, Sri Lanka. It was eight years before an article about the new mineral was published in 1961 and finally approved by the IMA and named after Mr. Ekanayake in 1967.

Ekanite is almost always completely metamict. Metamictization is a natural, gradual process of the complete destruction of the internal crystal structure of a mineral due to radiation present in the mineral or from nearby external radiation. Metamictization eventually leaves the mineral amorphous or without any internal crystal structure. Once this process is complete the mineral is desctibed as metamict.

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