Although cabochons could be cut from massive eudialite or translucent crystals, transparent material suitable for faceting is elusive and always small.
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|Crystallography||Hexagonal (trigonal); tabular crystals, may be hexagonal or trigonal; also prismatic, rhombohedral, massive.|
|Colors||Shades of brownish red, yellowish brown, pink, red. Often translucent.|
|Luster||Vitreous; greasy; may be dull.|
|Cleavage||Basal, indistinct; fracture uneven; brittle.|
|Stone Sizes||Faceted gems well under 1 carat in size have been cut from Quebec material. These are deep red and extremely rare. National Museums of Canada (Ottawa, Ontario): 0.30, 0.40 (intense red, Sheffield Lake, Quebec, Canada).|
|Formula||Na4( Ca,Fe,Ce,Mn)2ZrSi6O17(OH,CI)2 (Note: Eucolite= calcium-rich variety)|
|Pleochroism||Varies with body color.|
Optics: o= 1.591-1.623; e= 1.594-1.633.
Uniaxial (+) but sign variable (eucolite reported to be (-) with higher indices and S.G.).
Occurrence: Nepheline syenites and associated pegmatites:
Julienhaab District. Greenland: crystals up to I inch in length.
Kola Peninsula, USSR: Pilansberg. South Africa. Ampasibitika, Madagascar
Magnet Cove, Arkansas: rich red color, in feldspar.
Mt. Ste. Hilaire, Quebec, Canada: facetable (o = 1.596; e = 1.600; birefringence = 0.004).
Kipawa Complex. Sheffield Lake, Temiscamingue County,Quebec, Canada: red, facetable.
Sweden: o = 1.598; e = 1.604; Birefringence = 0.004; S.G. = 2.88.
Comments: Although cabochons could be cut from massive eudialite or translucent crystals, transparent material suitable for faceting is elusive and always small.
Name: From Greek words meaning easy to dissolve because of its easy solubility in acids.