Heulandite from Tambar Springs NSW
Heulandite is one of the more common zeolite minerals. It has very distinctive crystals, which are usually tabular, and is often in a coffin shape, with a wider centre, narrower edges, and flat top and bottom.
Since its original classification, Heulandite was always regarded as a single mineral species with a variable elemental makeup. The Zeolite Subcommittee of the IMA divided this mineral into individual subspecies of four members in 1997. Almost all Heulandite specimens in collections are Heulandite-Ca. A distinction among the different Heulandite types is rarely made, and the members are generally named Heulandite without further breakdown.
This specimen was unearthed in Tambar Springs which is a small town in the North West Slopes region of New South Wales, Australia. Approx 417 kilometres northwest of the state capital, Sydney and at the 2011 census, Tambar Springs and the surrounding area had a population of just 540.
The Tambar Springs locale is well known for zeolite specimens. An interesting fact on the area, specimens found in the area were thought to be Stilbite, however, all “stilbite” from here is in fact Stellerite.
What’s interesting about this specimen is that it came from the collection of Jack Stange. If anyone has any information on Jack, please let me know.
I acquired this specimen from Peter at Crystal Habit (now Kristallen) at the August 2016 Carlingford Show.
Chemical Formula: (Ca,Na)2-3Al3(Al,Si)2Si13O36 · 12H2O (general)
Collection ID #: JG0035
Colour: White, colourless, beige, brown, pink, and gray
Hardness: 3.5 – 4
Acquisition Date: 27th August 2016
Crystal System: Monoclinic
Lustre: Vitreous, Pearly
Dimensions: 61mm x 37mm x 44mm
Locale: Tambar Springs, NSW, Australia
Rarity of Mineral