Category Archives: Geology

Arenophilia

I have a confession to make.  I have become an arenophile.  Fortunately, it is not illegal (unless trespassing while doing it or if you are in Sardinia), and it should not be harmful to my health.  I would say it is generally not contagious, but I did catch it this past spring when Jim Rienhardt introduced us to the hobby in the Wayne County Gem and Mineral Club November 2018 newsletter and later at the March meeting.  I did not realize I was hooked until this summer.  While collecting minerals on club trips to Maine and in Michigan, I looked for sands to collect and proceeded to fill quart freezer bags at a few dozen locations along lakes, rivers, and even from glacial deposits.  You see an “arenophile” is a lover of sand.  The word is derived from the Latin “arena” (sand) and the Greek ”phil” (love).

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Hamlin State Beach .. and garnet sand

Last March, Jim Rienhardt brought his collection of some 270 sands to the WCGMC meeting and told us about arenophiles (sand collectors) (Reinhardt, 2018).  Jim repeated his presentation at the Rochester Academy of Science later that month.  At that meeting RAS member Paul Dudley brought along some sand he had collected from Hamlin State Beach some 50 years ago.  Paul’s sand was red and dominated by garnet, but full of other heavy minerals.  He told us that the sand had been collected during a college field trip late in the spring when Lake Ontario first started to recede from winter highs.

I parked that in my memory and on my calendar and on July 8th set out to find some “garnet” sand for myself.  I was not disappointed.  The first stop I made was at Area #5 at the west end of Hamlin State Beach.  The Lake level seemed to have dropped, perhaps a foot from its highest erosional cut.  And in the bank left when the lake level was highest was a 2-3 cm thick band of black and red sand.  I sampled and took pictures and moved to other areas of the park.

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Barrus Farm Pegmatite

The Barrus Farm pegmatite outside the small hamlet of Lithia, MA has become a regular stop on Wayne County Gem and Mineral Club’s western New England field trip each of the past three years.  It is not a large site and the pegmatite there has never been quarried, but it does hold a special place in the world of gemology.  It is the type locality for goshenite, which is white beryl.  Yale University mineralogist Charles Sheppard identified the Barrus Farm white beryl in 1884 and named it after the town of Goshen about 3 miles east of the location. Continue reading

An Elemental Celebration

Published in May 2018 Wayne County Gem and Mineral Newsletter

Contrary to what you may have thought in high school, the Periodic Table of the Elements was not created to torture high school chemistry students.  The idea was simple at first.  Aristotle considered a four element table way back in 330 BCE.  He identified earth, air, fire and water as the four elemental building blocks.  But others since have not been satisfied with his simple approach, and the list grew and with that came complexity.

By the 1700s some 30 elements had been isolated and described and that grew to over 60 by the middle of the 19th century.  And it was in the middle of the 19th century that several chemists and inventors working independently began to recognize patterns in those elements and began to organize them into lists and tables.  A Russian chemist named Dmitri Mendeleev had the foresight to recognize that the known elements should be organized on their atomic weight and he also set the elements into a two-dimensional grid based on common properties.  But it was his observations that the chart needed gaps for elements that had yet to be discovered that set him apart from others.  For this insight, Mendeleev is credited as the “father of the Periodic Table”.

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Glacial Erratics

Almost anywhere we wander in New York, we are apt to encounter glacial erratics, rocks that were transported to their current locations by the great sheets of ice that covered the state as recently as 10,000 years ago.  Typically we just step over, or walk around, these aberrant rocks.  That is, unless we trip on them, in which case we curse their existence before we move on.  Farmers detest them too, but will use them to build stone walls or cobblestone barns.  Once in a while we might notice something interesting in them and stop to smack them with our hammers or mauls.  Typically they resist such actions, providing us a reason to detest them even more.

But there are some really famous glacial erratic boulders in the world.  Some are famous for their size, others for their location.  Perhaps you have a favorite one?  I’ve selected a few to highlight.

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Fluorescent sodalite in Great Lake States

Perhaps you have heard of the latest collecting craze in the Upper Peninsula of Michigan?  Beach collectors who have generally restricted their collecting to agates, amygdaloidal basalt, and perhaps an occasional greenstone are now returning to the beach after dark with a long wave UV light source.  They are finding beach rocks that are bright yellow when subjected to a 365 nanometer long wave light source.  Apparently there are some beaches where these stones are relatively common.

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Morrisonite

All who attended the January workshop of the Wayne County Gem and Mineral Club acquired a nice unpolished slab of morrisonite jasper from the club collection.  Most present at the event struggled to identify the “best” piece remaining when their raffle number was drawn.  It was all so colorful and each piece was unique.  I went home with my piece and decided to learn a bit more about my newest acquisition.

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Porphyroblasts

Porphyroblast:  I’ve always thought that was such a neat word, maybe even interesting enough for a story.   Say it out loud three times (“pore-fur-o-blast, pore-fur-o-blast, pore-fur-o-blast”).  Now don’t you want to learn more, perhaps even own a few?

Porphyroblasts are those large recrystallized minerals that grow in the groundmass of a metamorphic rock, most typically in schists and gneisses.    In New York State, we immediately think of the bright red almandine-pyrope garnets in the gneissic rocks in the Gore Mountain area, but the truth is the metamorphic schists and gneisses throughout New York and New England often contain garnet porphyroblasts.    Unfortunately a lot of New York’s garnets are hosted in high-grade metamorphic gneiss and they don’t display crystal faces when the rocks are broken.  Nevertheless they are large, colorful and fun to collect.

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Collecting In-Between: Sand

Wayne County Gem and Mineral Club member Jim Rienhardt collects sand.  In the November WCGMC Newsletter he tells us how and why.  I thank him for letting me republish the article here.

by Jim Rienhardt:

Rock to sand to rock:  Rock collectors collect on both ends.  So do I, but I also collect from the middle – the sand.  And, I am not alone.  There are many, many people who collect sand and have tens of thousands of samples.  But why, isn’t sand uninteresting?  The same may be said by someone who doesn’t understand collecting rocks.

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Clay Concretions in Sharon, Vermont

About 15,000 years ago the final of four glacial advances stopped in central Connecticut and a large end moraine was established.  As the glacier retreated a large lake formed in what would become the Connecticut River Valley.  Varved (seasonal) clay/silt layers were deposited. Debris (fossils, sticks, leaves, etc.) carried in with the clay/silt became nucleation points for calcite cementation and concretions grew in the clays.  These unique concretions are now being exposed by erosion.  The locals call them “Fairy Stones” or “Mud Babies”.

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Lancaster, PA for pseudomorphs

On arrival the location does not look like a typical mineral collecting site.  There are not any rocks to be seen.  The GPS coordinates provided by Beard (2013) are smack in the middle of a cultivated field filled with small evergreen trees just off Fruitville Pike in Lancaster, PA.  The field is flanked on two sides by subdivision housing and on a third side by a pair of little league baseball fields.   Your first thought is that you botched the directions. Continue reading

The Hypathia Stone

We all dream of finding that special rock, one that is totally unique, one that can hold that center position on the top shelf of our mineral cabinet.   Yes, that perfect piece we can be proud to display while telling the story of how we found it.  In 1996, a geologist working for the Egyptian Geological Survey had his dream fulfilled.  Aly Barakat was studying Libyan desert glass formed 26 million years ago, presumably by a meteorite impact, when he made his incredible find.  As a geologist he knew that the colorful broken pebbles he found deep in the Saharan desert were unique, but it took more than two decades to learn how special they truly are. Continue reading

A Gastropod and Macrostrat

On occasion, cleaning out that old box of leftover and generally forgotten minerals from a past trip can provide an unexpected reward.  Last month I uncovered a box of rather ordinary wavellite specimens from the club visit to Mount Pleasant Mills, PA in April of 2016.  Among the cruddy and generally less than desirable wavellite discards I found a fossil gastropod that I had remembered collecting, but had pretty much forgotten.  It was time to clean it up and do a little research.  After all, that is what the winter months are for in western New York.

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Micro-micro minerals

Some rockhounds like to collect rocks and minerals the size of small cars, or at least motorcycles.  You know who you are (and so do the rest of us!).  Others settle for samples that can be carried, a size that seems to decrease with each collecting season.  But we also know of those who collect thumbnail specimens (less than 1”) and stick them into tiny boxes.  There are even folks who like to collect specimens that require microscopes to be seen; these collectors are called micromounters.  But I am going to tell you a bit about some “mineral specimens” that are even smaller.  And I am even going to make up a new name for them.  I am calling them micro-micro minerals.

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The Origin of the Elements

Have you ever sat down to think about where the chemical elements in all those neat minerals we collect came from?   I mean in the grand scheme of things, like as the universe forms and evolves.

We collect metallic minerals, like copper (Cu) in chalcopyrite and bornite and in colorful carbonate secondary minerals like malachite and azurite.  The latter require carbon (C) as does calcite with its calcium (Ca) cation and dolomite when there is sufficient magnesium (Mg).  WCGMC has travelled to Cobalt, Ontario in search of silver (Ag) in its pure form as well as cobalt in arsenic minerals (Co, As).

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