Macdonaldite
A variety of Minerals
What is Macdonaldite?
Macdonaldite is a rare barium silicate mineral with a chemical formula of BaCa4Si16O36(OH)2·10H2O. Macdonaldite was first described in 1965 and named for Gordon A. MacDonald (1911–1978) an American volcanologist at the University of Hawaii. Macdonaldite crystallises in the orthorhombic system. Macdonaldite is anisotropic with low relief. Macdonaldite appears as veins and fracture coatings in a sanbornite and quartz bearing metamorphic rock. Macdonaldite was first described in 1965 for an occurrence near the Big Creek-Rush Creek area in Fresno County, California. It has also been reported from Mariposa and Tulare counties in California. It has also been reported from a quarry in San Venanzo, Umbria, Italy.
Market Value Factors
Pricing varies for every rock and mineral, so use these universal factors to gauge Macdonaldite before comparing listings or appraisals.
Size & Weight
Larger, intact specimens usually command higher prices.
Rarity & Demand
Scarce material or popular varieties sell at a premium.
Condition & Finish
Chips, repairs, and heavy wear lower value; clean prep helps.
Treatment & Provenance
Untreated specimens with documented locality are prized.
Macdonaldite Localities Map
See where Macdonaldite is found with a localities map, collecting zones, and geology context. Generate a sample map preview below.
Quick Facts
Physical Properties
- Color
- White, colourless.
- Hardness (Mohs)
- 3.5 - 4
Chemical Properties
- Chemical Formula
- BaCa4Si16O36(OH)2 · 10H2O
- Elements
- Ba, Ca, H, O, Si
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Macdonaldite FAQs
How do I identify Macdonaldite?
Macdonaldite can be identified by its hardness of 3.5 - 4 on the Mohs scale, White color. Look for these key characteristics when examining specimens.
What color is Macdonaldite?
Macdonaldite typically appears in White, colourless.. Color can vary depending on impurities and formation conditions.
How hard is Macdonaldite?
Macdonaldite has a hardness of 3.5 - 4 on the Mohs scale. This gives it moderate hardness.
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