| Cowlesite | |
| Category: | Zeolite minerals |
| Formula: | Ca(Al2Si3)O10·5-6H2O |
| Imasymbol: | Cow[1] |
| Strunz: | 8/J.24-10 |
| System: | Orthorhombic |
| Colour: | Colourless, White |
| Mohs: | 5-5.5 |
| Luster: | Vitreous |
Cowlesite is a mineral named after American mineralogist John Cowles. W.S. Wise and Rudy W. Tschernich first described it in material from roadcuts along Neer Road, Goble, Oregon, United States. The description also incorporated data from Superior, Arizona. It most often occurs as small colorless to white spheres in basalt, and is often associated with other zeolites.