Achyrophanite is a rare potassium sodium iron arsenate. It was approved as a distinct mineral species in 2018. It was first described from the Arsenatnaya fumarole, Kamchatka peninsula, Far-Eastern Region, Russia.
Hardness
6.5-7.5
Mohs
Luster
Vitreous
Transparency
Translucent
Is this achyrophanite?
4-step field checkRun through these checks against the specimen in your hand. The more boxes tick, the more confident the ID.
- 1Test the hardnessTry to scratch achyrophanite with a known reference. Achyrophanite sits at Mohs 6.5-7.5, softer than the next harder reference, harder than the previous one.
- 2Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 3Match the color rangeCompare against the expected color range: dark brown, brownish-red.
- 4Look at form & habitCrystal system: orthorhombic.
Often confused with
Achyrophanite vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside achyrophanite
Minerals reported to co-occur with achyrophanite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- (K,Na)₃(Fe³⁺,Ti,Al,Mg)₅O₂(AsO₄)₅
- Mohs hardness
- 6.5-7.5
- Density
- 3.8-4.1 g/cm³
- Colors
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Orthorhombic
- Rarity
- Rare
- Uses
- Collector
- Host rock
- metamorphic rocks
Where rockhounds find achyrophanite
Classic worldwide localities
- Arsenatnaya fumarole, Second scoria cone, Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka peninsula, Far-Eastern Region, Russia
Field-hunting tip
Where it forms: metamorphic rocks. If you start seeing quartz, biotite, feldspar in float, you are in the right ground.
Common questions
How do you identify achyrophanite?+
Mohs hardness is 6.5-7.5. Luster: vitreous. Common colors include dark brown, brownish-red.
Where is achyrophanite found?+
Notable localities include Arsenatnaya fumarole, Second scoria cone, Northern Breakthrough of the Great Tolbachik Fissure Eruption, Tolbachik volcano, Kamchatka peninsula, Far-Eastern Region, Russia.
Is achyrophanite safe to handle?+
Achyrophanite contains arsenic and calls for real care. Contains arsenic, which is toxic if ingested or inhaled as dust. Wash hands thoroughly after handling and avoid creating dust.
What rocks look like achyrophanite?+
Achyrophanite is most often confused with Almandine, Spessartine, Andradite. A quick hardness test and a streak check separate the look-alikes faster than color alone.
What minerals are found with achyrophanite?+
Achyrophanite commonly co-occurs with Quartz, Biotite, Feldspar. Spotting any of these in float or country rock is a useful trip signal.
What kind of rock does achyrophanite form in?+
Where it forms: metamorphic rocks. Working float back to the host body is the standard way to chase a fresh occurrence.
What is achyrophanite used for?+
Achyrophanite is used in collector.
Find achyrophanite on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
