| Armstrongite | |
| Category: | Phyllosilicate |
| Formula: | CaZr[Si<sub>6</sub>O<sub>15</sub>]·3H2O |
| Imasymbol: | Asg[1] |
| Strunz: | 9.EA.35 |
| System: | Monoclinic |
| Color: | Dark to light brown |
| Cleavage: | Perfect on, good on |
| Tenacity: | Very brittle |
| Mohs: | 4.5 |
| Luster: | Vitreous |
| Streak: | Brownish white |
| Diaphaneity: | Translucent |
| References: | [2] |
Armstrongite (CaZr[Si<sub>6</sub>O<sub>15</sub>]·3H2O)[2] is a silicate mineral.
It was first described in 1973 from an occurrence at Dorozhnyi pegmatite, Khanbogd District, Ömnögovi Province, Mongolia.[3] It was named for the American astronaut Neil Armstrong.