Nitratine is a soft, water-soluble nitrate mineral that typically forms as efflorescent crusts or granular masses in extremely arid climates. Due to its high solubility, it is almost exclusively found in hypersaline desert environments like the Atacama Desert, where it remains protected from rainfall.

Hardness

1.5-2

Mohs

Luster

Vitreous

Streak

White

Transparency

Transparent

mineralrare

Nitratine

Also: Soda Niter, Chile Saltpeter

Hardness: 1.5-2
Luster: Vitreous
Streak: White
Transparency: Transparent

Is this nitratine?

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 nitratine with a known reference. Nitratine sits at Mohs 1.5-2 — softer than the next harder reference, harder than the previous one.
2
Check the streak
Drag the specimen across an unglazed porcelain plate. Nitratine leaves a white streak.
3
Read the luster
Hold the specimen under a strong light. Nitratine typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: white, colorless, yellowish, reddish-brown.
5
Look at form & habit
Crystal system: trigonal. Typical habit: massive, crusts, granular, rarely rhombohedral crystals.

Often confused with

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

mineral

Calcite

Mohs 3

How to tell apart: Calcite is the harder of the two (Mohs 3 vs. 1.5-2).

Often found alongside nitratine

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

All properties

Chemical formula: NaNO₃
Mohs hardness: 1.5-2
Density: 2.26 g/cm³
Colors: White Colorless Yellowish Reddish-brown
Streak: White
Luster: Vitreous
Transparency: Transparent
Crystal system: Trigonal
Crystal habit: Massive, Crusts, Granular, Rarely Rhombohedral Crystals
Cleavage: Perfect Rhombohedral
Rarity: Rare
Uses: Industrial, Fertilizer, Collector
Host rock: Arid Sedimentary Environments and Evaporite Deposits
Typical price: $20-100 per specimen

Where rockhounds find nitratine

Classic worldwide localities

Atacama Desert, Chile
Tarapaca, Chile
Antofagasta, Chile
Pampa del Tamarugal, Chile

Field-hunting tip

Look in arid sedimentary environments and evaporite deposits country — that is the host setting where nitratine typically forms. If you start seeing halite, gypsum, anhydrite in float, you are in the right ground. Field specimens usually show a massive, crusts, granular, rarely rhombohedral crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify nitratine?+

Mohs hardness is 1.5-2. It typically shows a vitreous luster. The streak is white. Common colors include white, colorless, yellowish, reddish-brown.

Where is nitratine found?+

Notable localities include Atacama Desert, Chile; Tarapaca, Chile; Antofagasta, Chile; Pampa del Tamarugal, Chile.

How much is nitratine worth?+

Typical asking prices fall in the range of $20-100 per specimen. Quality, size, and provenance can move individual specimens well outside that range.

What rocks look like nitratine?+

Nitratine is most often confused with Calcite, Halite. A quick hardness test and a streak check separate the look-alikes faster than color alone.

What minerals are found with nitratine?+

Nitratine commonly co-occurs with Halite, Gypsum, Anhydrite, Iodargyrite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does nitratine form in?+

Nitratine typically forms in arid sedimentary environments and evaporite deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is nitratine used for?+

Nitratine is used in industrial, fertilizer, collector.

Find nitratine on the map

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