Mendozite is a relatively rare sulfate mineral that forms in arid environments as a secondary product of sulfide oxidation. It typically appears as white, fibrous encrustations or efflorescent crusts and is highly soluble in water, requiring careful storage in low-humidity environments.
Is this mendozite?
5-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch mendozite with a known reference. Mendozite sits at Mohs 2.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Mendozite leaves a white streak.
- 3Read the lusterHold the specimen under a strong light. Mendozite typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: colorless, white.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: fibrous, massive, or encrusting.
Often confused with
Mendozite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside mendozite
Minerals reported to co-occur with mendozite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- NaAl(SO₄)₂·11H₂O
- Mohs hardness
- 2.5
- Density
- 1.76 g/cm³
- Streak
- White
- Luster
- Vitreous
- Transparency
- Transparent
- Crystal system
- Monoclinic
- Crystal habit
- Fibrous, Massive, Or Encrusting
- Cleavage
- Poor
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Oxidized Zones of Sulfide Ore Deposits
- Typical price
- $20-100 for small specimens
Where rockhounds find mendozite
Classic worldwide localities
- San Juan Province, Argentina
- Chile
- California, USA
Field-hunting tip
Look in oxidized zones of sulfide ore deposits country, the host setting where mendozite typically forms. If you start seeing alunogen, pickeringite, gypsum in float, you are in the right ground. Field specimens usually show a fibrous, massive, or encrusting habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify mendozite?+
Where is mendozite found?+
How much is mendozite worth?+
What rocks look like mendozite?+
What minerals are found with mendozite?+
What kind of rock does mendozite form in?+
What is mendozite used for?+
Find mendozite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
