The Mineral meionite
Meionite is the calcium-rich end member of the Scapolite series. It is very similar and often indistinguishable from Marialite, the other end member of the series. Intermediary forms of Meionite and Marialite are frequent, and these are classified simply as Scapolite. Of the two Scapolite minerals, Meionite is the more prevalent form. Meionite is named for the Greek word meion (μειον), which translates as "minus", in reference to its lesser termination angles when compared to Vesuvianite.
Chemical Formula
Ca4(Al6Si9O24)(CO3)
Color
White, gray, colorless, cream, yellow, bluish-gray, and purple. Less commonly blue, brown, green, red, and pink.
Crystal System
Tetragonal
Properties
Streak
White |
Hardness
5 - 6 |
Transparency
Transparent to opaque |
Specific Gravity
2.6 - 2.8 |
Luster
Vitreous to dull |
Cleavage
2,2 |
Fracture
Conchoidal, uneven |
Tenacity
Brittle |
Other ID Marks
Often fluorescent, sometimes brightly. Colors include white, yellow, and pink. Fluorescence may be present both in shortwave and longwave. |
Noteworthy Localities
The two Scapolite members often occur together and are not usually individually
distinguished. See Scapolite for a comprehensive list of localities general to the Scapolite series.
Distingushing Similar Minerals
Meionite - Difficult to distinguish without chemical analysis.
Feldspars - Often form in different crystal habits, lacks fluorescence.
Nepheline - Different cleavage, lacks fluorescence.