Mendozite

A variety of Minerals

Mendozite specimen

What is Mendozite?

Mendozite is a sulfate mineral, one of the alum series, with formula NaAl(SO4)2·11H2O. It is a hydrated form of sodium aluminium sulfate (soda alum). It was discovered in western Argentina in 1868, probably near San Juan. The exact location has been lost, but was described as "San Juan, near Mendoza", and it is the latter city that give the mineral its name. It occurs in evaporites, presumably from the oxidation of sulfide minerals in the presence of clays. It is very soluble in water, and so can only be found in dry regions: however, in can still effloresce (lose water of crystallisation) in extremely arid climates, altering to tamarugite (the hexahydrate).

Market Value Factors

Pricing varies for every rock and mineral, so use these universal factors to gauge Mendozite 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.

Applies to all rocks & minerals.

Mendozite Localities Map

See where Mendozite is found with a localities map, collecting zones, and geology context. Generate a sample map preview below.

Map preview
North ZoneCentral RidgeSouth Basin

Interactive map layers and collecting notes are available in the app.

Quick Facts

Physical Properties

Color
Colourless (turns white upon exposure); colourless in transmitted light.
Hardness (Mohs)
3

Chemical Properties

Chemical Formula
NaAl(SO4)2 · 11H2O
Elements
Al, H, Na, O, S

Also Known As

MendoziteNatrumalaun
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Mendozite FAQs

How do I identify Mendozite?

Mendozite can be identified by its hardness of 3 on the Mohs scale, Colourless (turns white upon exposure); colourless in transmitted light. color. Look for these key characteristics when examining specimens.

What color is Mendozite?

Mendozite typically appears in Colourless (turns white upon exposure); colourless in transmitted light.. Color can vary depending on impurities and formation conditions.

How hard is Mendozite?

Mendozite has a hardness of 3 on the Mohs scale. This makes it a soft mineral that can be scratched easily.

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