Properties
| Category | Inoborates |
|---|---|
| Formula | Ca2B5SiO9(OH)5 |
| Crystal system | Monoclinic |
| Color | White, colorless |
| Crystal habit | Massive to nodular, occurs as tabular prisms flattened parallel to |
| Cleavage | None |
| Fracture | Conchoidal, uneven |
| Mohs scale hardness | 3.5 |
| Luster | Subvitreous, glimmering |
| Streak | white |
| Diaphaneity | Translucent |
| Specific gravity | 2.53 – 2.59 |
From the Wikipedia article
Howlite, a calcium borosilicate hydroxide (Ca2B5SiO9(OH)5), is a borate mineral found in evaporite deposits.
Source
Source record: crystal-compendium/howlite/minerals.json. Fetched from English Wikipedia by the operator 2 October 2026.
https://en.wikipedia.org/wiki/Howlite — revision id 1288288268. Text and properties from Wikipedia, licensed CC BY-SA 4.0.