thomsonite


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thomsonite

[′täm·sə‚nīt]
(mineralogy)
NaCa2 Al5Si5O20·6H2O Snow-white zeolite mineral forming orthorhombic crystals and occurring in masses of radiating crystals; hardness is 5-5.5 on Mohs scale.
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Figure 5k shows the occurrence of neddle-like crystals of thomsonite along with botroidal and fibrous spheroidal Fe-oxyhydroxides A fibrous and reticulate aggregate which is transparent to translucent having a variety of colours ranging from white to yellow to reddish gray, can be attributed to levyne (Figure 5l).
Thomsonite appears as long tabular crystals (up to 1.
Thomsonite crystals were described by Hibsch (1915) from a strongly vesicular facies of the highest lava flow at the base of Pusty vrch Hill (490 m a.
Automorphous microphenocrysts resembling so-dalite are completely zeolitized (to thomsonite and gonnardite).
Thomsonite is generally massive or fibrous, beige to off-white.
The paragenetic sequence of the zeolite mineralization at this locality is calcite(I) [right arrow] chabazite [right arrow] thomsonite [right arrow] mesolite [right arrow] analcime [right arrow] calcite(II) [right arrow] illite.
Name: For the relationship to other members of the thomsonite series.
Thomsonite was identified from the Millington quarry for the first time in 1997.
Thomsonite occurs in the cleft fillings as transparent, platy crystals to 2 mm.
Extinction Sign of Zeolite Angle, Degrees Elongation Natrolite 0 + Thomsonite 0 +/- Scolecite 18 - Mesolite 8 +
The thomsonite is particularly good for the species because it occurs in quite large, sharp, transparent crystals.
Thomson [Thomas Thomson, 1773-1852, after whom thomsonite was named] who, having analyzed and described it, gave it a name after its proprietor [owner, that is, Allan] not knowing at the time the person to whom it would have been more handsome and more correct to have done that honour [i.