CompuServe Messages

Ferrierite hunt in CA

    06-Nov-94 22:11:46
Sb: Ferrierite hunt in CA
Fm: Doug Mitchell 70621,702
To: all
Hi, folks– While I was visiting Calif. recently, I managed to visit the Kanan Rd. area noted for ferrierite among other minerals, in the company of Rod Burroughs, who led me to a new ferrierite site near the old one. This is the area of the type(?) locality for rare ferrierite and dachiardite – if I seem to ignore the latter it is because it is harder to distinguish and not fluorescent, while ferrierite is an uncommon fluorescent among the zeolites. Westbound on the Ventura freeway, we simply went south from the Kanan Rd. exit (it leads toward Point Dume near Malibu), 1.7 miles from the freeway. Parking on a right (west) side turnout just before topping a rise in the road, we saw two people collecting off the east side of the road, where a small basalt quarry was evident on the slope of the rise. One was Bob Housley (did I get that right, Rod?), who had told Rod about the place; on hearing I was after ferrierite he showed me to one small outcrop shortly north of the quarry, and to the road cut atop the rise, as places where ferrierite is found. He pointed out to me one cavity in the road cut that had ferrierite – I mined it out as best I could, and that was the only ferrierite I know I found. At this place, its fluorescence seems present but minor compared to the nearby locality. While that was the only ferrierite I managed to collect, I did come up with a number of pieces of calcite, chalcedony, and whatever that were fluorescent. The road cut was solid walls of what I took to be basalt; the Encyclopedia of Minerals says the ferrierite is found in this area (Agoura hills) in "andesitic breccia". As I wandered along the road cut walls, pounding lots of basalt loose, I found myself wishing for the hammer of Thor – as it was, I had only a standard-size rockpick Rod had lent me, with a pair of chisels. I found a number of calcite (aragonite?) bodies and veins, and seams of chalcedony (opal?). These proved interesting after darkness fell, soon after we arrived. Unlike the site further south where calcite seams fluoresce a pretty pink with yellow-white layers, here, the most massive calcite fluoresced bluish-white, phosphorescing similarly, LW and SW, while the thin layers were more white, orange, and pink, with an overall orange-white look. There were also seams of colorless translucent chalcedony (opal?) that fluoresced a pretty blue with a hint of green SW and white LW, with a greenish-blue phosphorescence (somewhat odd fluorescent behavior for chalcedony, more likely from opal, though it looks more like chalcedony to me otherwise). If the fluorescence was calcite behind/within the translucent chalcedony/opal, I cannot catch the culprit in the act, as none of it seems to come to the surface for an acid test. I am inclined to think it is the chalcedony/opal. A great deal of pounding, with a certain amount of minor skin-breaking of my left hand (I forgot to pack the work gloves I had set aside) by misses, broke lose one particularly nice specimen where a half-inch chalcedony/opal vein is bracketed by thin seams of calcite/aragonite, with a nice complementing of fluorescent colors. I later found it has one small cavity in the calcite with some flat white plates reminiscent of cleavelandite (albite), but which bend in irregular curves. This is small, and needs the microscope I do not have, to reveal all that may lurk within. We then tried for the older ferrierite site, 1.1 miles south of the freeway, a boulder-strewn field, but could not locate it as it was dark, and new construction in the area had confused the landmarks (if not covered over the site). A GPS unit and coordinates for the site would have been very helpful. Those Agoura hills are a treasure trove for a fluorescent mineral collector. –Doug