Paracelsian
Barium aluminosilicate (BaAl2Si2O8)
A rare barium aluminosilicate that is a monoclinic polymorph of celsian, found in barium-rich metamorphic and manganese deposits.
- Mohs hardness
- 6
- Color
- Colorless, white, to pale yellow or pink
- Type
- mineral
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Overview
Paracelsian is a rare barium feldspar with the same composition as celsian, BaAl2Si2O8, but a different crystal structure—it is a polymorph built on the danburite structure type rather than the feldspar framework of celsian.
It forms colorless to white prismatic or tabular crystals and granular masses, and is monoclinic. Because barium rarely becomes concentrated enough to form its own silicates, paracelsian is uncommon and largely confined to specialized geological settings.
It is closely associated with celsian and other barium minerals and is mainly of interest to mineralogists and collectors.
Formation & geology
Paracelsian forms in barium-enriched metamorphic environments, especially metamorphosed manganese ore deposits and barium-rich sedimentary rocks subjected to regional or contact metamorphism.
The barium is generally inherited from baryte (barium sulfate) in the protolith. During metamorphism and hydrothermal activity, barium is mobilized and incorporated into aluminosilicate phases, crystallizing as paracelsian or its polymorph celsian depending on conditions of temperature and pressure.
Notable localities include the Benallt manganese mine in Wales, UK, and barium-rich occurrences in Italy and elsewhere, typically alongside celsian, baryte, and manganese silicates.
How to identify it
Paracelsian is colorless, white, or pale yellow to pink, with a vitreous luster, white streak, and Mohs hardness around 6. It forms prismatic to tabular crystals with good cleavage.
It is visually indistinguishable from celsian, with which it shares an identical chemical formula; only X-ray diffraction reliably separates the two polymorphs.
Its association with barium minerals (baryte, celsian) and manganese ores is a useful contextual clue, but confirmation requires laboratory analysis rather than field tests.
Uses & significance
Paracelsian has no industrial or gem applications. It is too rare to serve as a barium ore, and its crystals are not used in jewelry.
Its importance is scientific, illustrating polymorphism in barium aluminosilicates and providing a marker of barium-rich metamorphic conditions.
Well-formed paracelsian crystals are valued by systematic mineral collectors for their rarity and as companions to celsian in barium mineral suites.
Frequently asked questions
How is paracelsian different from celsian?
They have the same formula (BaAl2Si2O8) but different structures—paracelsian has a danburite-type framework, while celsian has a true feldspar structure; they are polymorphs.
Is paracelsian a feldspar?
It is the same composition as the barium feldspar celsian but is technically a separate polymorph, so it is often described as a feldspar-related barium aluminosilicate.
Where is paracelsian found?
In barium-rich metamorphic rocks and manganese deposits, with the Benallt mine in Wales being a classic locality.
Can paracelsian be used as jewelry?
No. It is rare, small, and has no ornamental or commercial value.
Paracelsian guides
In-depth guides for identifying, valuing, and understanding Paracelsian.
Paracelsian identified by the community
Real specimens identified with Rock Identifier.
