| Dachiardite-K | |
| Category: | Tectosilicate, Zeolite |
| Formula: | K4(Si20Al4O48)·13H2O |
| Imasymbol: | Dac-K[1] |
| System: | Monoclinic Unknown space group |
| Unit Cell: | a = 18.67, b = 7.51 c = 10.23 [Å], β = 107.79° (approximated) |
| Color: | Snow-white |
| Habit: | Needle-like crystals in spherical aggregates |
| Cleavage: | (100), perfect |
| Fracture: | Stepped across |
| Tenacity: | Brittle |
| Mohs: | 4 |
| Refractive: | nα=1.48, nβ=1.48, nγ=1.48 (approximated) |
| Opticalprop: | Biaxial (+) |
| 2V: | 65o (measured) |
| Dispersion: | Distinct |
| Pleochroism: | No |
| Density: | 2.18 (measured), 2.17 (calculated; approximated) [g/cm<sup>3</sup>] |
| References: | [2] |
Dachiardite-K is a rare zeolite-group mineral with the formula K4(Si20Al4O48)•13H2O.[3] It is the potassium-analogue of dachiardite-Ca and dachiardite-Na, as suggested by the suffix "-K".[4] [5] Dachiardite honors Italian geologist and mineralogist Antonio D'Achiardi.
Dachiardite-K was discovered in opal-chalcedony veins in Eastern Rhodopes, Bulgaria. It is associated with barite, calcite, clinoptilolite-Ca, clinoptilolite-K, celadonite, dachiardite-Ca, dachiardite-Na, ferrierite-K, ferrierite-Mg, ferrierite-Na, mordenite, and smectite.