Sejkoraite-(Y) is an extremely rare secondary mineral from the mixite group that occurs as delicate, acicular radiating clusters. It is primarily identified by its distinctive yellow color and formation within hydrothermal arsenic-rich veins, most notably found at the Jáchymov locality in the Czech Republic.
Is this sejkoraite-(y)?
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 sejkoraite-(y) with a known reference. Sejkoraite-(Y) sits at Mohs 3 — softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Sejkoraite-(Y) leaves a yellowish-white streak.
- 3Read the lusterHold the specimen under a strong light. Sejkoraite-(Y) typically shows a vitreous luster.
- 4Match the color rangeCompare against the expected color range: yellow, greenish-yellow.
- 5Look at form & habitCrystal system: hexagonal. Typical habit: acicular or fibrous radial aggregates.
Often confused with
Sejkoraite-(Y) vs. its common look-alikes — and how to tell them apart in the field.
How to tell apart: Streak differs — Sejkoraite-(Y) leaves yellowish-white, Mixite leaves white.
How to tell apart: Streak differs — Sejkoraite-(Y) leaves yellowish-white, Agardite-(Y) leaves white.
How to tell apart: Streak differs — Sejkoraite-(Y) leaves yellowish-white, Zálesíite leaves white.
Often found alongside sejkoraite-(y)
Minerals reported to co-occur with sejkoraite-(y). Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- YCu₆(AsO₄)₃(OH)₆·3H₂O
- Mohs hardness
- 3
- Density
- 3.8-4.0 g/cm³
- Colors
- Streak
- Yellowish-white
- Luster
- Vitreous
- Transparency
- Translucent
- Crystal system
- Hexagonal
- Crystal habit
- Acicular or Fibrous Radial Aggregates
- Cleavage
- None
- Rarity
- Rare
- Uses
- Collector
- Host rock
- Hydrothermal Veins
- Typical price
- $50-300 per specimen
Where rockhounds find sejkoraite-(y)
Classic worldwide localities
- Jáchymov (Czech Republic)
Field-hunting tip
Look in hydrothermal veins country — that is the host setting where sejkoraite-(y) typically forms. If you start seeing arsenopyrite, annabergite, quartz in float, you are in the right ground. Field specimens usually show a acicular or fibrous radial aggregates habit, so train your eye for that shape before scanning the outcrop.
Common questions
How do you identify sejkoraite-(y)?+
Where is sejkoraite-(y) found?+
How much is sejkoraite-(y) worth?+
Is sejkoraite-(y) safe to handle?+
What rocks look like sejkoraite-(y)?+
What minerals are found with sejkoraite-(y)?+
What kind of rock does sejkoraite-(y) form in?+
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Find sejkoraite-(y) on the map
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