Eudialyte is a fairly rare cyclosilicate mineral with forms in alkaline igneous rocks. Its name derives from the Greek eu and dialytos, meaning "well decomposable", which alludes to its ready solubility in acid.  It unfortunately rarely forms good crystals and only occasionally forms any crystal faces at all. Eudialyte is usually embedded in the host rock, surrounded by other minerals. The mineral's colors on the other hand are quite pleasant and give the collector an all-together attractive and rare mineral. It can show distinctive colors of a red-violet, pink, blue, yellow and an attractive brown. Crystals are usually translucent to transparent and give a vitreous luster. Eudialyte tends to be fractured and is rather brittle.

Much eudialyte on the market today comes from the Kola Peninsula, Russia. The site at Kola Peninsula is one of several sites around the world that have a strange assortment of igneous minerals and are referred to as Agpaitic Pegmatites. Eudialyte is an example of an unusual mineral that comes from these mineralogically unique sites. Not only is it rich in sodium, but has zirconium, cerium and often traces of yttrium in its structure. Other localities of eudialyte include Mont Saint-Hilaire in Canada and some sites in Greenland, Norway and Arkansas.

Eudialyte is considered to be a potential source of zirconium in the future. Another use of eudialyte is as a gemstone, but this use is limited by its rarity and very poor crystal habit. These factors make eudialyte of primary interest as a collector's mineral.

Characteristics:

Chemistry: Na4(Ca, Ce, Fe, Mn)2ZrSi6O17(OH, Cl)2, Sodium Calcium Cerium Iron Manganese Zirconium Silicate Hydroxide Chloride
Class: Silicates
Hardness (Mohs scale): 5 – 5.5
Density: 2.8 – 3
Crystal system: trigonal
Crystal Habit: typically embedded grains and distorted rhombohedral crystals
Transparency: transparent to translucent
Luster: vitreous
Cleavage: poor, one-directional (basal)