A beautiful Aussie Prehnite Slab. This material is an unusual green colour that is hard to capture in photos.
Wave Hill, NT, Australia.
8.6cm x 5.3cm x 1cm, 100g.
Prehnite: Ca2 Al2 Si3 O10(OH)2
Calcium Aluminum Silicate Hydroxide.
Prehnite is often found with zeolites and is sometimes thought of as a zeolite. But zeolites are actually Tectosilicates and Prehnite is a member the Phyllosilicates Subclass. Like zeolites, Prehnite can give off water when heated, but can not gain the water back like they can. Like most zeolites, Prehnite is formed as a result of low grade metamorphism usually from hydrothermal solutions. Crystals can be found in cavities of mafic igneous rocks. Typical formations are rather thick crusts with a rough or crystalin
Its colour is a pleasant green and is at times quite unique to Prehnite. Some Minerals that can be confused with Prehnite include Gyrolite, Smithsonite and Hemimorphite. Prehnite is harder than all of these and lacks Smithsonite’s unusual luster. Hemimorphite is usually blue and Gyrolite is not as glassy. Prehnite can be associated with many beautiful minerals and can make a fine specimen on its own. Its color, luster, associations and crystal habits make it a joy to own. An attractive collection mineral that is occasionally used for ornamental stone purposes and jewellery.