Properties
| Category | Tectosilicate minerals |
|---|---|
| Formula | (Na,Ca,K)5−6[Al8−9Si27−28O72]·nH2O |
| Crystal system | Monoclinic ; More than one space group |
| Color | colourless, yellow, green, white, pale pink |
| Crystal habit | tabular, parallel aggregates |
| Cleavage | perfect basal |
| Mohs scale hardness | 3.5–4 |
| Luster | pearly, vitreous |
| Streak | white |
| Diaphaneity | transparent to translucent |
From the Wikipedia article
Heulandite is the name of a series of tectosilicate minerals of the zeolite group. Prior to 1997, heulandite was recognized as a mineral species, but a reclassification in 1997 by the International Mineralogical Association changed it to a series name, with the mineral species being named:Heulandite-Ca Heulandite-Na Heulandite-K Heulandite-Sr Heulandite-Ba.
Source
Source record: crystal-compendium/heulandite/minerals.json. Fetched from English Wikipedia by the operator 2 October 2026.
https://en.wikipedia.org/wiki/Heulandite — revision id 1335906015. Text and properties from Wikipedia, licensed CC BY-SA 4.0.