Wayne County Gem and Mineral Club’s September Adirondack field trip was another great success. Seven spots in 4 days with the Saturday AM visit to Benson Mines in Star Lake attracting the most collectors. 33 folks convened and enjoyed a morning collecting in the dumps of the open-pit iron mine just outside town. Five of the other sites visited were repeats for the club (Rose Road, Benson Mines, Talcville, Valentine Mine, Fine roadcut, and Moose River). However, we had never been to the Seavey Road marble quarry north of Gouverneur. Thanks to Ken St. John, who had visited earlier with a small group of fluorescent mineral collectors, and to quarry owner Kevin Dibble, we were able to spend three hours in the large, and very white, quarry. As a new site for us, the Seavey Road location deserves a review.
October is another month with two official birthstones. If you are partial to wondrously terminated hard crystalline faceted gemstones, perhaps tourmaline would be your preferred choice. But, if you like the rainbow play of colors offered by opal, then stones cut to display the remarkable lustrous character of precious opal may touch your fancy. Since I’ve already written about tourmaline, let’s focus on opal in this birthstone review.
I have trouble finding one lone whole trilobite when I go out collecting in the Devonian of New York. And then along comes this note from central Poland where researcher Blazej Blazejowski reports that the eyeless trilobite Trimerocephalus chopini can be found preserved in trains with head to tail (or in trilobite lingo with cephalon to pygidium). He infers that the queues actually represent migratory chains as the ancient arthropods marched across the seafloor, perhaps in an unsuccessful effort to escape near and present danger.
Wouldn’t it be neat to find a queue of arthropods after splitting some Hamilton Group shales? Or maybe there was no reason for New York trilobites to migrate? Perhaps life was just too good to move?
Blazejowski, B., et. al., 2016 Ancient animal migration: a case study of eyeless dimorphic Devonian trilobites from Poland, Palaeontology, V. 59, p. 743-751.
So how would you like to wake up one morning and wonder how such a big rock got into your garden?
Where should I start? The 10 day August trip to Thunder Bay and back again was a blast. We all returned with enough minerals and memories to last through the winter (or at least until our trip to the Adirondacks in September!).
But first and foremost: Just as the 1959 stamp Issue in the header was a joint issue of the USA and Canada, this trip was a two country trip with WCGMC and the Niagara Peninsula Geological Society (NPGS) of St. Catharine’s, Ontario. Those of us from WCGMC thank NPGS for allowing us to join them, and in particular to their field trip leader Ashley Pollock, who planned the itinerary and set up the many visits requiring permission and outside leadership.
People come in all sizes and so do collectible rocks and minerals. There are collectors who prefer garden rocks, as big as they can carry (or even bigger). These people will do this until their yards or patios are completely covered by rocks. And then they start building piles. You know who you are! There are folks who like cabinet specimens of several inches. You need space to display these also and typically quality cabinet specimen can deplete the wallet all too quickly.
Me, I prefer mineral specimens that are called miniatures, no longer than 2” in their longest dimension. A few dozen can fit on a display shelf or in a drawer. Of course there are thumbnail collectors who specialize in specimens that can fit into a one inch cube. They even have neat little special boxes, called Perky boxes named after the collector/dealer that popularized the theme. And then there are the micromounters. These collectors can purchase much of their material less expensively and the number of available minerals seems endless, but then they require binocular microscopes and perhaps close-up camera lens to best view their prized possession.
But what about collecting minerals on thin section. Is there a place for that? OK, first off what is a thin section? According to the bible of the internet, Wikipedia tells us that a thin section is a “laboratory preparation of a rock, mineral, soil, bone, or even metal for use with a polarizing microscope”. Fine, but what is it? Let me try: a thin section is a tiny sliver of rock, typically mounted/glued onto a microscope slide that permits light to pass through all the transparent mineral phases. As it turns out if you mount a polished rock surface onto a glass microscope slide and grind/polish the surface down to 30 microns in thickness (that’s about 1/800th of an inch for the metrically challenged) then many minerals will display characteristic colors and properties upon the transmission of polarized light. In this way minerals can be identified under the microscope. Further-more their textures and how they are intergrown with each other can be used to interpret how the minerals grew and how a rock might have formed.
I have written about Green’s Landing east of Canandaigua Lake after each of my summer visits the past 4 years. This time I will keep the words to a minimum and illustrate a wonderful joint trip with mostly pictures.
July was a busy month for Bill Lesniak and his travelling rock and mineral kit stand. If you have not seen his operation, Bill sets up at whatever event will allow him and, on the behalf of Wayne County Gem and Mineral Club, offers free rock and mineral kits to youngsters. They do have to earn them though. They must cut out labels, display dexterity with glue sticks to apply them to the egg cartons he provides and then, with help, locate the 12 specimens (this summer: 6 rocks, 4 minerals and 2 fossils). In the end they go home with something that looks like this:
Published in the August WCGMC newsletter
Olivine is one the most common rock-forming silicate minerals on our glorious planet. It is found in iron and magnesium rich igneous rocks, both extrusive rocks like basalt (think Hawaii) and intrusive equivalents like gabbro and deep mantle rocks called peridotite.. When it is found transparent and unfractured, olivine can be faceted into a brilliant green gemstone. We call that gemstone peridot and it is the August birthstone.
Olivine Group minerals are nesosilicates, meaning that their mineral lattice consists of isolated silica tetrahedral that are connected by interstitial cations (most commonly iron and magnesium). This leads to the formula (Mg, Fe)2SiO4. End member Mg-bearing olivine is the mineral forsterite, while Fe-dominated olivine is the mineral fayalite. The term chrysolite is sometimes used to label intermediate composition olivine. Most olivine contains both magnesium and iron, but Mg-rich forsterite is more common than fayalite.
Many thanks to Stephen Mayer for writing this collecting trip note for the August WCGMC newsletter and also for allowing me to post it my blog.
By Stephen Mayer
Tammy and I are back from a vacation in the desert southwest. Naturally, we took some time between visits to National Parks to do a little fossil and mineral collecting in Utah. The setting and geology are quite different than in western New York.
Very thick shale and calcareous mudstones are widespread in Millard County, west-central Utah and contain some of the best Cambrian biotas in the world. Not only are there 505-520 million year old fossils abundant, but also recent volcanism in the same region has left its mark with abundant rocks and minerals. Specifically, well preserved trilobites and beautiful topaz crystals can be collected.
Published in the July WCGMC Newsletter
Admittedly, some of the Wayne County Gem and Mineral Club collecting trips are out of this world. However, that’s figurative speech as we have not yet actually figured out how to visit any true planetary bodies. No, Cobalt, Ontario does not count, not even Sudbury. But suppose we could travel to another planet to collect. What might we find? Let’s consider Mercury for starters.
When I ventured to New Hampshire and Maine with three other intrepid collectors in search of aquamarine, topaz, smoky quartz, and other pegmatite riches, we did not pass by the planet Mercury (see posting of June 30, 2016). However, we did find an interesting spot to collect a little graphite. The site is in extreme eastern New York between the northern end of Lake George and the southern end of Lake Champlain. Along Pulpit Road, one half mile east of Route 22 in Putnam, NY, a large pile of boulders lay just 50 feet off the roadside. Bob, Linda, and Gary provide scale to the boulders in the cover photo.
Published in the July WCGMC newsletter
Rubies are red, very red. Rubies are hard, very hard. In fact with a hardness of 9 on the Moh’s scale, they fall just below diamonds as the hardest natural mineral on earth. Ruby is also the birthstone for July, the seventh month in the Gregorian calendar.
Published in the June 2016 WCGMC Newsletter
All of us who live or travel in Wayne County in western New York State know it is easier to travel north-south than east-west. Most of us know that is due to the elongated hills called drumlins that cover much of the region. And we also know that those geomorphological features were formed by the continental glaciation that covered western New York with ice a mile thick until their final retreat 12,000 years ago.
BUT, did you know that until very recently, glacial geologists could not agree on exactly how these elongated parallel hills came into existence. It was known that the drumlin fields were aligned with the glacial flow and retreat, but it was unclear whether they represent debris built up progressively during glacial advance and retreat or whether they were sculpted out of older sediment from previous glacial deposits. The debate has raged for over 150 years.
Published in the June WCGMC newsletter.
It is not quite fair to the rest of us, but folks with a birthday in June get a choice of two major birthstones. Pearl is the original modern gemstone for the month, officially named as such in 1912 by the National Association of Jewelers. However, alexandrite has been since added as a June gem.
BOOK REVIEW: New York Rocks and Minerals: A Field Guide to the Empire State, by Dan and Bob Lynch (2016)
There is a new publication available entitled “New York Rocks and Minerals: A Guide to the Empire State”. It is authored by Dan and Bob Lynch and published by Adventure Publications of Cambridge, MN. The 2016 book is available online for less than $20 on Amazon.
For each of 105 rocks, minerals, and fossils found in New York State this book provides a page of pictures designed to illustrate the specimen’s most characteristic identifying traits and an opposing page providing information on environment, what to look for to identify it, size, color, occurrence, and a notes section with other pertinent information. The format and presentation is very easy to use. In addition, beginners should enjoy the several page overview of New York geology. The 14 page “Quick Identification Guide” based on color and then expanding into other properties may be just the ticket for some.
The end of April was an active and exciting period for Wayne County Gem and Mineral Club diggers with two trips, each of three days duration. While we wait for warmer weather to our north, the club ventured to the neighboring states to our south, New Jersey and Pennsylvania.
It seems we have been here before! The May gemstone is a repeat of the mineral beryl. Yes, emeralds are a different color than the March gemstone aquamarine, but mineralogically a beryl is a beryl is a beryl.
The striking green color of an emerald is caused by the introduction of just 0.1-0-5 percent chromium substituting into the aluminum spot of the beryllium silicate mineral. A small amount of vanadium is also present. It is truly amazing that just a fraction of a percentage of an element can impart such a striking difference in color. While the richness and intensity in color is paramount in valuing an emerald, the presence of visible inclusions is also important. Emeralds lacking inclusions to the eye are considered flawless and carry more value than those with visible inclusions.
It was not that long ago that Wayne County and the rest of western New York were located just south of the equator while basking in tropical temperatures. A large and shallow inland sea dominated the region with high mountains to the east and a shallow continental margin to the west. The sea was replete with life. Invertebrates dominated the sea bottom, corals and brachiopods filtered nutrients from the seawater to survive, while trilobites, cephalopods (squid), and a host of other scavenger and predator species roamed the benthic (sea bottom) region feeding on them. Numerous species of gastropods (snails) and bivalves (clams) were abundant also. The seas above were dominated by large armored fish (i.e. Dunkleosteus) and a multitude of smaller fish. It was the Devonian Period of earth’s history. It was the age of fish.