Paracelsian Identification Guide
How to identify paracelsian, a rare barium feldspar, and tell it from its polymorph celsian and from quartz.
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What Paracelsian Looks Like
Paracelsian is a rare barium aluminosilicate mineral (BaAl2Si2O8) and a polymorph of celsian - it shares the same chemistry but a different (monoclinic) crystal structure. It typically forms colorless, white, or pale gray transparent-to-translucent crystals with a vitreous luster. Crystals are commonly prismatic or tabular and may be twinned, resembling other feldspars. Because it is uncommon, it is mostly encountered in manganese ore deposits and skarns rather than in everyday rockhounding.
- Color: colorless, white, pale gray
- Transparency: transparent to translucent
- Luster: vitreous
- Habit: prismatic to tabular crystals, often in veins/cavities of Ba-Mn deposits
Step-by-Step Field ID Checklist
- Check the geologic setting - paracelsian occurs in barium-rich, often manganese-bearing metamorphic/hydrothermal deposits.
- Look for clear, glassy prismatic crystals with feldspar-like form.
- Hardness test. It is hard, ~6, scratching glass with difficulty.
- Look for cleavage. Two good cleavage directions like other feldspars.
- Note density. It feels heavy for a clear silicate due to barium.
- Confirm by lab. Distinguishing it from celsian requires X-ray/optical analysis.
Key Diagnostic Tests
- Mohs hardness: ~6.
- Streak: white.
- Cleavage: good in two directions (feldspar-like).
- Density: relatively high, ~3.3 g/cm3 (barium-bearing), heavier than common feldspar (~2.6).
- Definitive ID: XRD or optical microscopy to separate from celsian.
Common Look-Alikes and How to Tell Them Apart
- Celsian: identical composition but monoclinic with different structure; only lab methods (XRD, optics) reliably separate the two polymorphs.
- Common feldspars (albite, orthoclase): much lower density (~2.6); a heft and barium check distinguishes paracelsian.
- Quartz: no cleavage, slightly harder (7), and lower density; paracelsian has feldspar cleavage and higher density.
- Barite: softer (3-3.5), with characteristic high density and three cleavages; barite is a sulfate, not a silicate.
Where It Is Found
Paracelsian is rare and associated with barium- and manganese-rich deposits. Described occurrences include the Benallt mine in Wales (a manganese deposit) and similar Ba-Mn metamorphic/hydrothermal localities worldwide, typically alongside other barium silicates.
Frequently asked questions
What is paracelsian?
Paracelsian is a rare barium feldspar mineral (BaAl2Si2O8) that is a monoclinic polymorph of celsian, usually found as colorless to white crystals in barium- and manganese-rich deposits.
What is the difference between paracelsian and celsian?
They have the same chemical composition but different crystal structures; reliably separating the two polymorphs requires X-ray diffraction or optical microscopy.
How can you tell paracelsian from common feldspar?
Paracelsian is much denser (~3.3 g/cm3 versus ~2.6 for common feldspar) because of its barium content, while sharing similar hardness and cleavage.
Where is paracelsian found?
In barium-manganese deposits such as the Benallt mine in Wales and similar metamorphic-hydrothermal localities.
Paracelsian identified by the community
Recent Paracelsian specimens identified with Rock Identifier.
