Botryogen is a rare hydrous sulfate mineral that typically forms distinct botryoidal or reniform crusts in the oxidized zones of iron and copper sulfide mines. Collectors value it for its vibrant orange to deep red color and unique globular habit, though it is sensitive to humidity and must be kept in a stable environment.
Is this botryogen?
5-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 botryogen with a known reference. Botryogen sits at Mohs 2-2.5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: ocher-yellow.
- 3Read the lusterHold the specimen under a strong light. Luster: vitreous.
- 4Match the color rangeCompare against the expected color range: hyacinth red, ocher yellow.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: botryoidal, radial, reniform.
Often confused with
Botryogen vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Botryogen leaves ocher-yellow, Copiapite leaves pale yellow; luster reads vitreous on Botryogen and pearly on {010} on Copiapite.
How to tell apart: Streak differs, so Botryogen leaves ocher-yellow, Jarosite leaves pale yellow; luster reads vitreous on Botryogen and subadamantine to vitreous, resinous on fractures on Jarosite.
Often found alongside botryogen
Minerals reported to co-occur with botryogen. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- MgFe³⁺(SO₄)₂(OH)·7H₂O
- Mohs hardness
- 2-2.5
- Density
- 2.14 g/cm³
- Colors
- Hyacinth redOcher yellow
- Streak
- Ocher-yellow
- Luster
- Vitreous
- Transparency
- Transparent to translucent
- Crystal system
- Monoclinic
- Crystal habit
- Botryoidal, radial, reniform
- Cleavage
- {010}, perfect; {110}, good
- Rarity
- Uncommon
- Uses
- Collector
- Host rock
- A secondary mineral, which may be in great abundance, altered from pyrite, especially in arid climates
Where rockhounds find botryogen
Classic worldwide localities
- Redington mine, Knoxville, and at the Palisades mine, near Calistoga, Napa Co., California, USA
- Cornwall, Lebanon Co., Pennsylvania, USA
- Falun, Sweden
- Rammelsberg mine, near Goslar, Harz Mountains, Germany
- Antofagasta, at Chuquicamata, Quetena, west of Calama, and Alcaparrosa, near Cerritos Bayos, southwest of Calama, Chile
- Santa Elena mine, Quebrada de La Alcaparrosa, San Juan Province, Argentina
Field-hunting tip
Where it forms: A secondary mineral, which may be in great abundance, altered from pyrite, especially in arid climates. If you start seeing copiapite, amarantite, hohmannite in float, you are in the right ground. Typical habit: botryoidal, radial, reniform. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify botryogen?+
Where is botryogen found?+
What rocks look like botryogen?+
What minerals are found with botryogen?+
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Find botryogen on the map
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