Cuatrocapaite-(NH4) is a very rare ammonium copper sulfate mineral first identified in evaporite deposits in Mexico. It typically occurs as small, pale yellow, platy crystals forming in arid environments and is highly sought after by advanced mineral collectors.

Hardness

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrare

Cuatrocapaite-(NH4)

Hardness: 2
Luster: Vitreous
Streak: White
Transparency: Transparent

No image

Is this cuatrocapaite-(nh4)?

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 cuatrocapaite-(nh4) with a known reference. Cuatrocapaite-(NH4) sits at Mohs 2, 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.
4
Match the color range
Compare against the expected color range: yellow, pale yellow.
5
Look at form & habit
Crystal system: trigonal. Typical habit: platy crystals.

Often found alongside cuatrocapaite-(nh4)

Minerals reported to co-occur with cuatrocapaite-(nh4). Spotting these in float or country rock is a strong cue you are in the right ground.

All properties

Chemical formula: (NH₄)₃(NaMg□)(As₂O₃)₆Cl₆·16H₂O
Mohs hardness: 2
Colors: Yellow Pale yellow
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Trigonal
Crystal habit: Platy crystals
Cleavage: Perfect
Rarity: Rare
Uses: Collector
Host rock: evaporite deposits

Where rockhounds find cuatrocapaite-(nh4)

Classic worldwide localities

Cuatro Cienegas, Coahuila, Mexico

Field-hunting tip

Where it forms: evaporite deposits. If you start seeing gypsum, thenardite in float, you are in the right ground. Typical habit: platy crystals. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify cuatrocapaite-(nh4)?+

Mohs hardness is 2. Luster: vitreous. The streak is white. Common colors include yellow, pale yellow.

Where is cuatrocapaite-(nh4) found?+

Notable localities include Cuatro Cienegas, Coahuila, Mexico.

Is cuatrocapaite-(nh4) safe to handle?+

Cuatrocapaite-(NH4) contains arsenic and calls for real care. Wash your hands afterwards, never grind or breathe the dust, and store it apart from specimens you handle often.

What minerals are found with cuatrocapaite-(nh4)?+

Cuatrocapaite-(NH4) commonly co-occurs with gypsum, thenardite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does cuatrocapaite-(nh4) form in?+

Where it forms: evaporite deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is cuatrocapaite-(nh4) used for?+

Cuatrocapaite-(NH4) is used in collector.

Find cuatrocapaite-(nh4) on the map

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