Welcome to my Earthcache! An Earthcache is a special type of geocache where there is no container to find - instead you are looking for a unique geological feature of the area and need to answer questions, as well as posting a picture, in order to claim the find. The goal of this Earthcache is to educate visitors about Barre Granite, what makes it unique, where it comes from, and how it was formed. All observations can be made from the cemetery roadway near the entrance of Wildwood Cemetery in Salamanca, New York. Parking is available in the immediate vicinity of the location.
EARTHCACHE REQUIREMENTS
As with all of my ECs, I am not looking for PhD thesis level responses, but I am hoping that you take some time to enjoy the area and learn something new. Please include a list of all cachers with your answer, if answering for more than one caching name. There is no need to send individual answers.
To claim a 'find' for this Earthcache you must answer the following questions and send your answers in a message or email to the owner using the link at the top of the page. You can log your find with a photo at GZ. Send your answers to the tasks. I will be in contact if there is a problem, no need to wait for a response as long as the required photo is included in your log.
Observational Task
At GZ, you will be standing in front of a large, 29-foot tall monument called "In Memory of Our Dead Comrades". This is the monument you will want to make your observations from.
Questions to Answer
1. Observe the various colours of the monument, that are unique to Barre granite. What colour are the largest crystals you see, and how big is the largest one you see?
2. Eastimate how much of this monument is made up of different types of mica, how much is quartz, how much is feldspar, and how much is other minerals or impurities.
3. This monument features two visible forms of mica within the monument. After reading the text below, identify a sample of both of them, and describe them. How do you know which one is which? Which one is more plentiful?
4. Mandatory: Include a photograph of yourself, your GPS, a signature item, thumbs up, etc at the monument. You do not need to show your face in the photo, but your photo must be unique to you. If you are caching with a group you can use the same photo, but each log must upload a photo.
A little Bit of History About this Monument:
This monument was unveiled more than 125 years ago on May 30, 1899, as a tribute to the victims of the Civil war. The monument was furnished by the Forness Bros. of Salamanca, and was supposed to have cost about $2300 (which would be about $90,000 today) but is estimated to have cost several hundreds more by the time it was installed. This monument was said to have been built out of "The Best Dark Barre Granite available at the time), is more than 29 feet tall, 12 feet wide, and is topped with a 8-foot-tall granite statue of a "Soldier at Parade Rest".
But What is Barre Granite?
Granite is an igneous rock that we’ve used for building materials for thousands of years. It’s name comes from the Latin word “granum,” meaning “grain,” which refers to the grains of quartz and feldspar that define granite.
Barre granite is a Devonian granite, that is only found in one particular town - the town of Barre in Washington County, Vermont. Barre Granite is described it as a "fine granite, composed of quartz, feldspar, and mica. The mica is both muscovite and biotite." It is a fine to medium-grained gray granite with two distinct phases; the earlier of these, the "dark Barre" (such as the granite used to make this monument), occupies the southern part of the exposed granite masses; the later phase, the "light Barre", is slightly lighter in color, and is a comagmatic member of the sequence. It occupies the bulk of the exposed granite masses.
The Geology of Barre, Vermont
During the Devonian period of geologic history (419.2–358.9 million yearsago), there was a geologic event in which magma containing quartz, feldspar,and mica (both muscovite and biotite) rose up from lower in the Earth’s crust and slowly cooled, forming large crystals that can be seen with the naked eye. The resulting solid rock becoming the bedrock that now dominates the Barre area, Granite. One type of granite found in the area, "Barre Gray" granite, is sought after worldwide for its fine grain, even texture, and superior weather resistance, for use in buildings and architecture, monuments, and memorials.
The Barre granite district, three to six miles southeast of Barre, Vermont, covers an area of less than thirty square miles. This region is underlain by phyllites, impure limestones, impure quartzites, and calcareous mica schists of the Waits River formation, at least a portion of which is Ordovician in age. The Barre granite, of late Devonian age, cuts these metasedimentary rocks.
But what makes Barre Granite unique?
Mica minerals are known for their sheet-like structure and are commonly found in igneous, metamorphic, and sedimentary rocks. Barre Granite is unique from most other forms of granite because it contains two separate syptes of mica, muscovite and biotite, both of which can be seen with the naked eye.
Muscovite
Muscovite is the most common mica, found in granites, pegmatites, gneisses, and schists, and as a contact metamorphic rock or as a secondary mineral resulting from the alteration of topaz, feldspar, kyanite, etc. It is characteristic of peraluminous rock, in which the content of aluminum is relatively high.
Appearance: Muscovite is usually colorless, pale green, or brown. It has a glassy to pearly luster.
Properties: Known for its perfect cleavage, allowing it to split into thin, flexible, transparent sheets.
Uses: Muscovite is used in electrical insulators and as a fireproofing material due to its high dielectric strength.
More Information: Sheets of muscovite have high heat and electrical insulating properties and are used in the manufacture of many electrical components. Muscovite sheets were used for kitchen oven windows before synthetic materials replaced them.
Biotite
Biotite is a sheet silicate; iron, magnesium, aluminium, silicon, oxygen, and hydrogen form sheets that are weakly bound together by potassium ions. It is sometimes called "iron mica" because it is more iron-rich than phlogopite. It is also sometimes called "black mica" as opposed to "white mica" (muscovite).
Appearance: Typically black, dark brown, or dark green with a vitreous to pearly luster.
Properties: Like muscovite, biotite can be split into thin sheets. It is rich in iron and magnesium.
Uses: Biotite is mainly used for geological study to determine the thermal history of rocks.