Mckelveyite-(Y) is a rare carbonate mineral typically found as small, hexagonal platy crystals. It is most famous for its occurrences within the Green River Formation's oil shales and rare alkaline intrusive complexes like Mont Saint-Hilaire. Collectors prize it for its association with exotic rare-earth assemblages and its distinct fluorescence under ultraviolet light.
Is this mckelveyite-(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 mckelveyite-(y) with a known reference. Mckelveyite-(Y) sits at Mohs 3.5-4, 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: vitreous to dull.
- 4Match the color rangeCompare against the expected color range: yellow, black, greenish gray, white, gray.
- 5Look at form & habitCrystal system: triclinic. Typical habit: pyramidal.
Often confused with
Mckelveyite-(Y) vs. its common look-alikes, and how to tell them apart in the field.
Often found alongside mckelveyite-(y)
Minerals reported to co-occur with mckelveyite-(y). Spotting these in float or country rock is a strong cue you are in the right ground.
All properties
- Chemical formula
- NaCaBa₃Y(CO₃)₆·3H₂O
- Mohs hardness
- 3.5-4
- Density
- 3.25 g/cm³
- Streak
- White
- Luster
- Vitreous to dull
- Transparency
- Transparent to opaque
- Crystal system
- Triclinic
- Crystal habit
- Pyramidal
- Cleavage
- Indistinct
- Fluorescence
- Yellow under SW UV
- Rarity
- Rare
- Uses
- Collector
- Host rock
- A rare mineral formed near trona beds in the Green River Formation (Wyoming, USA); in a differentiated alkalic massif (Khibiny massif, Kola Peninsula, Russia)
Where rockhounds find mckelveyite-(y)
Classic worldwide localities
- Westvaco trona mine, the John Hay, Jr. Well No. 1, the Diamond Alkali Daco No. 3 and Reid No. 2 drillholes, the Perkins Green River No. 3 drillhole, and the Texas Gulf Sulfur mine, all near Green River, Sweetwater Co., Wyoming, USA
- Mont Saint-Hilaire, Quebec, Canada
- Khibiny and Sallanlatvi massifs, and the Vuoriyarvi carbonatite complex, Kola Peninsula, Russia
- Khanneshin carbonatite complex, Afghanistan
Field-hunting tip
Where it forms: A rare mineral formed near trona beds in the Green River Formation (Wyoming, USA); in a differentiated alkalic massif (Khibiny massif, Kola Peninsula, Russia). If you start seeing ewaldite, acmite, biotite in float, you are in the right ground. Typical habit: pyramidal. Train your eye for that shape before scanning the outcrop.
Common questions
How do you identify mckelveyite-(y)?+
Where is mckelveyite-(y) found?+
Is mckelveyite-(y) safe to handle?+
What rocks look like mckelveyite-(y)?+
What minerals are found with mckelveyite-(y)?+
What kind of rock does mckelveyite-(y) form in?+
What is mckelveyite-(y) used for?+
Find mckelveyite-(y) on the map
RockHoundR shows mapped rockhounding spots, access rules, and lets you log every find.
