Paragenesis and sucession of the minerals at Limberg bei Sasbach, Kaiserstuhl, Baden (Germany) |
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| The
Limburgite rock is
in parts very porous and contains enormous numbers of vugs of various
shape and size. Some are spherical but most are irregular shaped in
sizes from a few mm to 10 cm and may be larger. The
Limburgite rock matrix consists of many idomorph Augite
crystals up to two centimeters, embedded in a glass matrix and
yellow brown mostly altered Olivine. The Olivine shows sometimes small
idomorph crystals, and was first collected by Walchner in 1819, and
subsequent (1823) described as a new mineral species
"Hyalosiderite", based on crystal shape and gravimetric analysis.
Today it is considered as an altered variety of
Fe-rich Olivine. The walls of the vugs are partially
covered with an amourphous silica coating which was named
"Kieselsäurehydrogel" by Lorent (1933). Coated Augite crystals and
often visible on the sorface of the vugs. The amorphus coting is
folllowed by Montmorillionite of
various colours and by a sequenze of Zeolites in the order: Offretite,
Phillipste (spheres), Faujasite, Phillipsite as Crystals and
Cabazite. Small droplets of Opal may also be present nucleating
on
offretite resulting in "sea-urchin" like forms. Crusts and
hemispheres of Calcite
are common, but crystals are rare and etched. A second mineral
paragenesis at Limberg is that of Calcite, Haylite and Aragonite
which is mostly present in fissures and in vugs of a tuff found in
quarry VII. Lorent (1933) shows a picture with a vug of 15 cm. |
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| Limberg Faujasite Phillipsite Chabazite Offretite Hyalite Dolomite Calcite Aragonite Montmorillonite Paragenesis Literature |
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| Home | A
small vug in Limburgite from Quarry I, with Phillipsite coating aggregates of Montmorillonite. Field of view about 20 mm |
