Ezcurrite is a rare borate mineral typically found as white, tabular crystals or massive, granular aggregates in evaporite deposits. Collectors primarily identify it by its associations with other borate minerals in classic saline lake bed environments like the Tincalayu deposit in Argentina.

Hardness

3-3.5

Mohs

Luster

Vitreous to satiny

Streak

White

Transparency

Transparent

mineralrare

Ezcurrite

Hardness: 3-3.5
Luster: Vitreous to satiny
Streak: White
Transparency: Transparent

Is this ezcurrite?

5-step field check

Run through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.

1
Test the hardness
Try to scratch ezcurrite with a known reference. Ezcurrite sits at Mohs 3-3.5, softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Streak: white.
3
Read the luster
Hold the specimen under a strong light. Luster: vitreous to satiny.
4
Match the color range
Compare against the expected color range: colorless.
5
Look at form & habit
Crystal system: triclinic. Typical habit: tabular crystals, massive, granular.

Often confused with

Ezcurrite vs. its common look-alikes, and how to tell them apart in the field.

Often found alongside ezcurrite

Minerals reported to co-occur with ezcurrite. Spotting these in float or country rock is a strong cue you are in the right ground.

All properties

Chemical formula: Na₂B₅O₇(OH)₃·2H₂O
Mohs hardness: 3-3.5
Density: 2.053 g/cm³
Colors: Colorless
Streak: White
Luster: Vitreous to satiny
Transparency: Transparent
Crystal system: Triclinic
Crystal habit: Tabular crystals, massive, granular
Cleavage: {110}, excellent; {010}, good; {100}, {126}, fair; {110}, {101}, poor
Rarity: Rare
Uses: Collector, Research
Host rock: Probably formed from solutions derived from dehydration of borax in a discordant deposit in folded playa siltstones and sandstones

Where rockhounds find ezcurrite

Classic worldwide localities

Tincalayu borax deposit, Salar del Hombre Muerto, Salta Province, Argentina

Field-hunting tip

Where it forms: Probably formed from solutions derived from dehydration of borax in a discordant deposit in folded playa siltstones and sandstones. If you start seeing borax, kernite, halite in float, you are in the right ground. Typical habit: tabular crystals, massive, granular. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify ezcurrite?+

Mohs hardness is 3-3.5. Luster: vitreous to satiny. The streak is white. Common colors include colorless.

Where is ezcurrite found?+

Notable localities include Tincalayu borax deposit, Salar del Hombre Muerto, Salta Province, Argentina.

What rocks look like ezcurrite?+

Ezcurrite is most often confused with Kernite, Borax, Ulexite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with ezcurrite?+

Ezcurrite commonly co-occurs with Borax, Kernite, Halite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does ezcurrite form in?+

Where it forms: Probably formed from solutions derived from dehydration of borax in a discordant deposit in folded playa siltstones and sandstones. Working float back to the host body is the standard way to chase a fresh occurrence.

What is ezcurrite used for?+

Ezcurrite is used in collector, research.

Find ezcurrite on the map

RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.