Santarosaite is a rare copper oxide that forms vivid blue globules of leaf-like crystals. It occurs in the oxidation zone of a hydrothermal polymetallic vein deposit. Associated minerals include atacamite, malachite and wulfenite. It was first described from Santa Rosa mine, 15 km SE of Iquique, Atacama desert, Northern Chile.

Hardness

3.5

Mohs

Luster

Vitreous

Streak

Pale Blue

Transparency

Translucent

mineralrare

Santarosaite

Hardness: 3.5
Luster: Vitreous
Streak: Pale Blue
Transparency: Translucent

Is this santarosaite?

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 santarosaite with a known reference. Santarosaite sits at Mohs 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. Santarosaite leaves a pale blue streak.
3
Read the luster
Hold the specimen under a strong light. Santarosaite typically shows a vitreous luster.
4
Match the color range
Compare against the expected color range: vivid blue.
5
Look at form & habit
Crystal system: tetragonal. Typical habit: globules of leaf-like crystals.

Often confused with

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

mineral

Volborthite

Mohs 3-3.5

How to tell apart: Streak differs, so Santarosaite leaves pale blue, Volborthite leaves yellowish-green.

How to tell apart: Streak differs, so Santarosaite leaves pale blue, Mottramite leaves yellowish green; luster reads vitreous on Santarosaite and greasy on Mottramite.

Compare →

Often found alongside santarosaite

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

All properties

Chemical formula: CuB₂O₄
Mohs hardness: 3.5
Density: 3.96 g/cm³
Colors: Vivid Blue
Streak: Pale Blue
Luster: Vitreous
Transparency: Translucent
Crystal system: Tetragonal
Crystal habit: Globules of Leaf-like Crystals
Cleavage: None
Rarity: Rare
Uses: Collector
Host rock: Oxidized Copper-vanadium Ore Deposits

Where rockhounds find santarosaite

Classic worldwide localities

Santa Rosa mine, Atacama Region, Chile

Field-hunting tip

Look in oxidized copper-vanadium ore deposits country, the host setting where santarosaite typically forms. If you start seeing atacamite, chrysocolla, gypsum in float, you are in the right ground. Field specimens usually show a globules of leaf-like crystals habit, so train your eye for that shape before scanning the outcrop.

Common questions

How do you identify santarosaite?+

Mohs hardness is 3.5. It typically shows a vitreous luster. The streak is pale blue. Common colors include vivid blue.

Where is santarosaite found?+

Notable localities include Santa Rosa mine, Atacama Region, Chile.

Is santarosaite safe to handle?+

It contains toxic constituents. Contains copper, which is toxic if ingested or inhaled as dust. Wash hands thoroughly after handling and avoid creating dust. Handle with care, avoid grinding or breathing dust, and store separately.

What rocks look like santarosaite?+

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

What minerals are found with santarosaite?+

Santarosaite commonly co-occurs with Atacamite, Chrysocolla, Gypsum. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does santarosaite form in?+

Santarosaite typically forms in oxidized copper-vanadium ore deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is santarosaite used for?+

Santarosaite is used in collector.

Find santarosaite on the map

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