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Thornasite
1 in the gallery
Thornasite is a radioactive phyllosilicate mineral that forms prismatic crystals with a vitreous to waxy luster. It typically appears colorless to green and can exhibit a transparent to translucent appearance with a white streak. The mineral crystallizes in the trigonal system and often occurs as sheet-like structures consistent with its two-dimensional layered nature, reflecting its classification in the phyllosilicate group. Its fluorescence can display green to blue hues under ultraviolet light, adding an extra dimension for display and study.
- Formula
- Na12Th3[Si8O19]4·18(H2O)
- Rarity
- Ultra Rare
- Stability
- Moderately Stable
- Collector interest
- High Interest
- Classification notes
- Phyllosilicate Two-Dimensional Infinite Sheets with Other Than Six-Membered Rings
Key characteristics
- Crystal system
- trigonal
- Mohs hardness
- 3–4
- Specific gravity
- 2.62
- Luster
- vitreous, waxy
- Transparency
- transparent, translucent
- Color
- colorless, green
- Streak
- white
- Cleavage
- none
- Fracture
- subconchoidal, uneven
- Crystal habit
- prismatic
- Fluorescent: green, blue
- Radioactive
About Thornasite
Notable specimens of Thornasite have been found in environments where complex silicate matrices and rare-earth elements coexist, contributing to its distinctive crystal habits and localities that collectors seek out for their rarity and scientific interest. The combination of clear to pale color, prismatic habit, and the mineral’s fluorescent properties makes it a compelling choice for display and mineralogical study, particularly for enthusiasts focused on radioactive minerals and silicate sheet structures.
