Strontiopharmacosiderite is a rare member of the pharmacosiderite group, characterized by its distinct cubic habit and yellowish hues. It is a secondary mineral typically found in the gossan zones of arsenic-rich hydrothermal deposits, often occurring as small pseudocubic crystals. Due to its arsenic content, collectors should exercise caution during handling and storage.

Hardness

2.5

Mohs

Luster

Vitreous

Transparency

Translucent

mineralrarePharmacosiderite Group family

Strontiopharmacosiderite

Hardness: 2.5
Luster: Vitreous
Transparency: Translucent

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Is this strontiopharmacosiderite?

4-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 strontiopharmacosiderite with a known reference. Strontiopharmacosiderite sits at Mohs 2.5, softer than the next harder reference, harder than the previous one.
2
Read the luster
Hold the specimen under a strong light. Luster: vitreous.
3
Match the color range
Compare against the expected color range: yellow, greenish-yellow, yellowish-brown.
4
Look at form & habit
Crystal system: tetragonal. Typical habit: pseudocubic crystals, granular aggregates.

Often confused with

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

mineral

Pharmacosiderite

Mohs 2.5

How to tell apart: Luster reads vitreous on Strontiopharmacosiderite and adamantine to greasy on Pharmacosiderite.

How to tell apart: Scorodite is the harder of the two (Mohs 3.5-4 vs. 2.5).

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Often found alongside strontiopharmacosiderite

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

All properties

Chemical formula: Sr₀.₅Fe₄[(AsO₄)₃(OH)₄]·4H₂O
Mohs hardness: 2.5
Colors: Yellow Greenish-yellow Yellowish-brown
Luster: Vitreous
Transparency: Translucent
Crystal system: Tetragonal
Crystal habit: Pseudocubic crystals, granular aggregates
Rarity: Rare
Uses: Collector
Host rock: oxidized zones of arsenic-rich hydrothermal mineral deposits

Where rockhounds find strontiopharmacosiderite

Classic worldwide localities

La Plâtrière quarry, Granges, Wallis, Switzerland (type locality)

Field-hunting tip

Where it forms: oxidized zones of arsenic-rich hydrothermal mineral deposits. If you start seeing arsenopyrite, goethite, limonite in float, you are in the right ground. Typical habit: pseudocubic crystals, granular aggregates. Train your eye for that shape before scanning the outcrop.

Common questions

How do you identify strontiopharmacosiderite?+

Mohs hardness is 2.5. Luster: vitreous. Common colors include yellow, greenish-yellow, yellowish-brown.

Where is strontiopharmacosiderite found?+

Notable localities include La Plâtrière quarry, Granges, Wallis, Switzerland (type locality).

Is strontiopharmacosiderite safe to handle?+

Strontiopharmacosiderite contains arsenic and calls for real care. Contains arsenic. Wash hands thoroughly after handling and avoid inhaling dust or powder.

What rocks look like strontiopharmacosiderite?+

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

What minerals are found with strontiopharmacosiderite?+

Strontiopharmacosiderite commonly co-occurs with Arsenopyrite, Goethite, Limonite. Spotting any of these in float or country rock is a useful trip signal.

What kind of rock does strontiopharmacosiderite form in?+

Where it forms: oxidized zones of arsenic-rich hydrothermal mineral deposits. Working float back to the host body is the standard way to chase a fresh occurrence.

What is strontiopharmacosiderite used for?+

Strontiopharmacosiderite is used in collector.

Find strontiopharmacosiderite on the map

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