The structure actually contains open channels that allow water and large ions to travel into and out of the crystal structure. The size of these channels controls the size of the molecules or ions and therefore a zeolite like mordenite can act as a chemical sieve, allowing some ions to pass through while blocking others. Mordenite forms fine sprays of radial acicular crystal clusters that look like pin-cushions or snowballs. On top of other interesting and beautiful associated minerals, mordenite can be extremely striking. Mordenite is definitely a must have especially for the dedicated zeolite collector.
Color is colorless, white, yellow, pink and red.
Luster is vitreous to silky and pearly. Crystals are transparent to translucent. Crystal Habits include sprays of radial acicular crystal clusters that can remind someone of pin-cushions or snowballs. Individual crystals are prismatic to acicular and striated vertically. Aggregates can be radiating, fibrous, columnar and encrusting.