Local geologic structures include a local anticline and tension fractures. Local rocks include rocks of the Franciscan Complex, unit 1 (Coast Ranges). Associated with Upper Cretaceous rocks of the Santa Teresa Hills. Wallrock alteration is moderate (carbonitization). Primary ore control was lithology (serpentinite contact) and the secondary control was fracturing. The primary mode of origin was hydrothermal activity related to crustal thinning in the wake of the northward migration of the Mendocino Triple Junction about 14.5 Ma. Ore bodies generally conform to the silica-carbonate replacement of serpentinite thought to be intrusive into the Franciscan rocks, but now known to be structures associated with older subduction processes then complicated (dissected) by dextral faulting associated with the still-active San Andreas fault system. Rock contacts are highly sheared and irregular. The ore bodies are primarily cinnabar replacement in fractured silica-carbonate rock surrounded by sedimentary rocks of the Jurassic-Cretaceous Franciscan complex. ![]() The deepest exploratory working is the Church shaft sump and drift on the 750 meter (2450 ft.) level below the former peak of Mine Hill. The two deeper ore bodies (North and South Randol (misnomer, respectively east and west)) trend N25W and dip at about a 45-degree angle to a maximum depth of about 610 meters (2000 ft.) below the peak of Mine Hill (formerly 535 meters (1755 ft.) AMSL, now 527 meters (1730 ft.) AMSL). The shallower central mine workings under Mine Hill (called the main mine) are irregular and strike N-S to N15E to a depth of about 244 meters (800 ft.) below the peak. Mineralization is a Hg deposit primarily hosted in Late Cretaceous serpentinite and tuffaceous rocks metasomatized to so-called silica-carbonate rock. Bailey and Everhart (1964) is by far the best and most thorough description. Principle geological descriptions of the mine pre-date modern theory of plate tectonics. The property was sold by New Idria Mining and Chemical Company to the County in parcels, with the final parcel (Mine Hill) transferred in mid-1975. MRDS database stated accuracy for this location is 1,000 meters. ![]() Small quantities of mercury were produced from ore starting at this time. Claimed by Andrés Castillero in late-1845. Antonio Suñol and Louis Chaboya tried unsuccessfully to identify the ore in 1824 and are credited with the "discovery" of the mine. The peoples introduced the ore and vermillion paint to 18th-Century settlers at Mission Santa Clara de Asís. First worked in prehistorical times by indigenous peoples to collect cinnabar to make vermillion paint. The former mine is on land owned by Santa Clara County and open to the public as Almaden Quicksilver County Park. The peak of Mine Hill (527 meters (1730 ft.) AMSL) above the main mine workings is 2.1 km (1.4 mile) N92.4W of center of Casa Grande manor house in New Almaden and about 17 km (11 miles) N166.7E from old downtown main post office (now art museum) in San Jose. You can see more work by the artists I painted with here: Uma Kelkar, Laurie Wigham, Srivani Narra Ward, and Iva Sikirica Ilić.A former Hg occurrence/mine complex located in secs. I like the idea of looking at a scene, deciding what I want to capture of it and then going from there: it lets me paint the very same scene, but a little bit differently each time.Īnd that was about it for our paintout. In this first piece, my main interest was that bank of mist just below the mountains.Īnd in this second one, I’m looking at those clouds in the sky. I’ve hiked this trail countless times and never stopped to even sketch the view: the nice thing about painting at a group paintout is that the person planning and picking spots may pick something you never would, and that forces you to look at the scene with new eyes, to paint what you would have otherwise overlooked. The effect, I think, is like Sumi-e ink, but with the sheen and softness of graphite.įrom later in the day, two more paintings, both of this view. A stick is great for drawing, the tin allows you to paint with a brush. With graphite, I like the kind in the tin better than the stick. The neutrals in this next piece are done with Art Graf, which is water soluble graphite, on a wet backdrop of watercolor. It took patience to wait and add in those last dark branches, and even they weren’t on totally dry paper. These ghostly trees were interesting to paint on paper that never dried out. Cameras are deceptive, my photos from the day don’t capture the mist… Can you spot at least 4 painters in this photo? There’s a 5th in the parking lot, not in the photo, and I’m #6. Visibility was low, humidity was high and the view we planned on painting was hidden in the mist. ![]() We picked what was probably the foggiest morning in the South Bay. A couple of weeks ago, I painted with friends at Almaden Quicksilver County Park.
0 Comments
Leave a Reply. |