No regional zoning of zeolite assemblages was apparent in this study Figure 8 shows that the zoning sequence and textural evidence suggest the following crystallisation sequence: first K-rich clay (nontronite) followed by K-rich mica (celadonite), carbonate (calcite), cryptocrystalline silica (e g chalcedony), then thomsonite followed by chabazite, analcime, phillipsite
and wairakite, and natrolite, laumontite, and stilbite-type minerals (stilbite and stellerite) Zeolites' stability ields are known from modern hydrothermal systems (Kristmannsdottir and Tomasson, 1978) and the observed sequence in the samples studied here conformed to a progressive decrease in temperature favouring hydrothermal system hydration.
Figure 3 shows the phillipsite
morphology and the XRD powder diffraction profiles from montmorillonite alteration.
Incrustation of phillipsite-Ca and smectite on gismondine results from possible chemical interaction between gismon-dine, phillipsite
and residual solution.
Robie, Thermodynamic Properties of Zeolites; Low- Temperature Heat Capacities and Thermodynamic Functions for Phillipsite
and Clinoptilolite; Estimates of the Thermochemical Properties of Zeolitic Water at Low Temperature, Am.
Using the FJPZ50 sample as starting material, a progressive loss of its amorphous character turned it into a synthesis product characterised by the appearance of relative poorly crystalline phillipsite
only after 96 hours.
ER Natrojarosite VR VR Natrolite VR VR Olivine group VR C Paratacamite ER ER Phillipsite
series ER ER Phlogopite VR ER VR Pseudorutile VR VR VR Pyrite C C C C C C Pyrochlore VR ER?
The best, with sharp, lustrous crystals up to 3 mm, were collected at the beginning of the 1990's in braunite veins, associated with carbonates, barite and, in places, phillipsite
A group of us speculated as to whether the unknown was one species or another; suggestions included leifite, nenadkevichite, apatite, dawsonite, natrolite, phillipsite
, strontianite, and aragonite.
The X-ray powder diffraction pattern is similar to that of phillipsite
. The bladed crystals are well-formed, and appear to have monoclinic or triclinic symmetry.
Turning finally to the zeolites, Carati lists just four: scolecite, thomsonite, phillipsite
The type localities for no less than eight of the approximately 49 known zeolites (barrerite, dachiardite, gismondine, merlinoite, montesommaite, phillipsite
, pollucite, and willhendersonite) are within its borders.
[(K,Na,Ca).sub.1-2][(Si,Al).sub.8][O.sub.16] [multiplied by] 6[H.sub.2]O