Zeolites from Eburru Station, Central Rift Valley, Kenya

The Eburru Station zeolite locality (white circle on photo) is located about 2 km. northwest of Eburru Station on the road to Elmenteita where it crosses a line of hydrothermal vents exposing the deposits in the road cut. Here the vent passes through a flow of basalt filled with small vugs. Deposition in the vugs is widespread but zeolites have formed only in a narrow band. The most common is Chabazite in cubes and twinned cubes. There are three other zeolites or zeolite-like minerals present. All are colorless and porous. Below, you will find SEMs of some of these zeolites. Larger crystals 1 to 2 mm.


Follow the image links for more SEMs

Chabazite (colorless)
    Striated & unstriated triclinic twins
    Interpenetration twins (unstriated)
    Interpenetration twins (striated)
    Modified triclinic twins
    Contact twins on 1011
    Triclinic rods (could be heulandite or laumontite) (?)

Stilbite, var. Stellerite
    Radial clusters forming semispheres. Colorless.
    Flat, fan-shaped arrays of crystals. Colorless.
Unidentified Zeolites (colorless)
    Cubic rods (posibly chabazite or heulandite).
    Parallelogram rods (possibly heulandite).
    Overlapping, arallelogram plates (possibly heulandite).
    Parallelogram plartes w/corners truncated (possible heulandite).
    Picket fence xls in stacks (possible heulandite).
    Plates twinned in three axes to form pyramids.
Calcite
    White to colorless, sometime etched.
    Translucent, very pale blue, but resistant to acid (may not be calcite)

Unidentified Associated Minerals
    Translucent, slightly bluish, calcite-like xls forming rings around vugs
    Long fiberous, furry xls (possibly thompsonite or calcite)
    Short fiberous clusters of grain-like plates
    Scarlet red to orange massive or minute crystals
    Branching, coarl-like aggregates in brown and dull orange
    Off white to pale blue, grey-green & brown clay minerals

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