Goedkenite is a very rare phosphate mineral that occurs in complex pegmatite environments. It is primarily found as small, yellow to colorless tabular crystals or delicate radiating clusters associated with other phosphate minerals at the type locality in South Dakota.
Is this goedkenite?
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 goedkenite with a known reference. Goedkenite sits at Mohs 5, softer than the next harder reference, harder than the previous one.
- 2Check the streakDrag the specimen across an unglazed porcelain plate. Streak: white.
- 3Read the lusterHold the specimen under a strong light. Luster: subadamantine.
- 4Match the color rangeCompare against the expected color range: colorless, light yellow.
- 5Look at form & habitCrystal system: monoclinic. Typical habit: tabular crystals, radiating aggregates.
Often confused with
Goedkenite vs. its common look-alikes, and how to tell them apart in the field.
How to tell apart: Streak differs, so Goedkenite leaves white, Tavorite leaves pale green; luster reads subadamantine on Goedkenite and vitreous on Tavorite.
How to tell apart: Luster reads subadamantine on Goedkenite and vitreous to resinous on Triplite.
Often found alongside goedkenite
Minerals reported to co-occur with goedkenite. Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- Sr₂Al(PO₄)₂(OH)
- Mohs hardness
- 5
- Density
- 3.83 g/cm³
- Colors
- Streak
- White
- Luster
- Subadamantine
- Transparency
- Semitransparent
- Crystal system
- Monoclinic
- Crystal habit
- Tabular crystals, radiating aggregates
- Cleavage
- On {100}, fair
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare late-stage secondary hydrothermal mineral in a complex granite pegmatite
Where rockhounds find goedkenite
Classic worldwide localities
- Palermo #1 mine, near North Groton, Grafton Co., New Hampshire, USA
Field-hunting tip
Where it forms: A rare late-stage secondary hydrothermal mineral in a complex granite pegmatite. If you start seeing palermoite, childrenite, bjarebyite in float, you are in the right ground. Typical habit: tabular crystals, radiating aggregates. Train your eye for that shape before scanning the outcrop.
Common questions
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Find goedkenite on the map
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