RocksdayHowlite vs Magnesite
How to tell them apart
A white borate with gray to black web-like veins. Its porosity makes it easy to dye.
Photo: Robert M. Lavinsky, CC BY-SA 3.0
Magnesium carbonate, usually as white porcelain-like masses with a cauliflower texture.
Photo: Robert M. Lavinsky, CC BY-SA 3.0
Quick tests
- Acid (vinegar or dilute HCl): Magnesite fizzes weakly, or only when powdered or warmed; Howlite doesn't.
Key differences
- Magnesite fizzes in warm acid and is harder.
- Howlite has gray web-like veins and doesn't fizz.
Side by side
| Property | Howlite | Magnesite |
|---|---|---|
| Type | Mineral | Mineral |
| Mohs hardness | 3–3.5 | 3.5–4.5 |
| Luster | Subvitreous to dull | Vitreous to dull |
| Streak | White | White |
| Colors | White, Gray | White, Gray, Yellow |
| Crystal system | Monoclinic | Trigonal |
| Specific gravity | 2.53–2.59 | 3 |
| Formula | Ca₂B₅SiO₉(OH)₅ | MgCO₃ |
| Found in | Windsor, Nova Scotia; Tick Canyon, California | Liaoning, China; Austria |
Properties that are the same for both are grayed out.
How to identify howlite
- Chalky white with thin gray or black veins.
- Soft — a knife scratches it.
- Doesn't fizz in acid.
Crystal system: Monoclinic
Full Howlite guide →How to identify magnesite
- Chalky to porcelain-white, often knobbly.
- Fizzes only in warm acid or as powder.
- Harder than calcite.
Crystal system: Trigonal
Full Magnesite guide →More comparisons
Could you tell them apart from a blurry close-up?
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