Stone Map EarthCache

This is an Earth cache, so there is no container hidden at the coordinates.
To claim credit for this cache, read the text below, visit the given coordinates and email me answers to the questions in the logging requirements at the end of this listing.

Accessibility
This Earth Cache is only accessible during the Flag House Museum opening hours. At the time of publishing this cache listing, the opening hours are Tuesday-Saturday, 10AM to 4PM.
Please check the Star Spangled Banner Flag House website for current opening hours to avoid disappointment.
You will need to have a close look at the stone map to be able to claim credit for this Earth cache. The stone map is located in the front yard of the Flag House which is accessible through the gate on 844 East Pratt Street. You don't need to pay any fees to access the courtyard. This gate is locked when the museum is closed, do not enter the property if the gate is not open.

The making of the Stone Map
The idea of laying a map made of stones originating in respective US states came from the first curator of the Flag House, Mr. Arthur Sewell. He didn't live long enough to see his dream project begin, but his wife pursued the efforts to make his idea happen. It wasn't until 1950 that the Flag House Association succeeded in persuading William Lane, the Governor of Maryland, to mail every US state governor asking for help: Each state received a paper pattern indicating how to cut the stone. The stones were then to be shipped to Baltimore along with a contribution of $100 (which equals about $1100 in 2021) to finance the assembly of the map.
Some states were faster than others to respond - Maine was the first to comply and delivered a stone within several weeks from the request, while other states didn't even react. New Mexico was the last one to deliver a stone, only after some nudges from the American Legion's adjutants.
It took until 1955 for each and every stone to be received in Baltimore. The stones varied in size and thickness, some by 1-3 inches, which required a fair amount of work for the masons to trim them and make adjustments in order for the stones to fit into a concrete foundation. Pictured below is the master mason, photographed by The Baltimore Sun.

More than 10 years after the project started, the 27 x 17 foot map was finished. However, several US states or territories are not represented by a stone, because they only joined the Union while the map-making was already in progress. There are two bronze stars on the map which stand for Alaska and Hawaii and the District of Columbia is represented by a coin struck from copper originating from the US frigate Constellation.
On Flag Day, 18th June 1961, the stone map, framed by blocks of marble, was ceremonially dedicated.

              The rocks, minerals and other elements found in the Stone Map

Minerals
Minerals are defined as natural, inorganic homogenous substances. Besides a scientific name they can be referred to by an element symbol or a chemical formula. Currently about 3800 minerals are known and described, however this number keeps rising, as every year approximately 50 new minerals are discovered and studied. Only 300 minerals occur naturally on a large scale.
Minerals are classified into nine groups according to their chemical components and inner structure. For the purpose of this Earth Cache, we will focus on non-metallic, elemental minerals.
A rock consists of minerals and can be formed by a single mineral, but more commonly a mixture of minerals. Almost 99% of all rocks on Earth are formed by (mixtures of) only 30 minerals, which shows how variable minerals are - a different structure of the mineral's atoms leads to forming different forms of the same mineral. This is called allotropy - the atoms of the same chemical element (mineral) are arranged in a different manner. A mineral can have two or more allotropes.

Carbon (C, carbonium) is the only element that is found in all forms of life on Earth, animals, plants, humans. Best known are the allotropes of carbon: diamond and graphite, both are pure carbon, but differ immensely in hardness, colour and opacity. Diamond consists of carbon atoms arranged in a tetrahedral lattice, while graphite is formed by carbon atoms being arranged in sheets of flat hexagonal lattices. Such a "simple" factor as atom arrangement also determines the price: What if your old-school graphite pencil suddenly turned into a diamond? Or if the expensive ring you saved money for for several months to gift to a loved one now is nothing but a writing utensil?

Silicon (Si, silicium) is the 8th most common element in the Universe. One of the most common and most important mineral rocks is an oxide of silicon: silicon dioxide = SiO₂ = silica in mineralogy and well-known under its popular name quartz. Quartz forms many polymorph rocks, known as silicates. Polymorphism means that a solid material can exist in more than one form or crystal structure. This is a principle similar to allotropy of the chemical elements.
Silicates encompass the largest group of minerals and form the most important component of the Earth's crust (forming about 90% of the crust), as well as occurring in meteorite rocks. Naturally most commonly occurring on Earth as a rock compound are the following silicates: feldspar, mica, garnet, amphibole, talc, orthoclase and pyroxenes.

Granite is a rock built on silicium: it consists mainly of quartz and feldspar, with some small amounts of mica and amphiboles, some other minerals can also be admixed. Mica is a silicate mineral, that can be split into very thin layers. It can be seen in granite as small shiny crystals. Amphiboles are also silicate minerals, containing sodium, calcium, magnesium, iron and aluminium, but in contrast to mica, amphiboles are of a prism-like shape and structure. Because of its components, granite usually is of gray, white, pink or red colour.

From Maine to Virginia
These two rocks are an example of dynamic metamorphism, a process of rock transformation by forces of pressure and heat, which shear, crush, fold, bend or flatten the rocks. The size of resulted mineral grains depends on the force causing the metamorphosis: the higher the heat or pressure, the larger the grains will be.
It begins with a sedimentary rock shale, which is subjected to gradual metamorphism:

Shales and mudstones in a sedimentary basin are compressed by horizontal forces with some minor heating. The clay minerals are modified into shale and mudstone by these forces and heat. As this happens, layers are formed by a process called foliation: mineral grains align themselves at right angles to the compressive forces. This results into a vertical foliation that usually crosses the bedding planes that existed in the original shale.

Slate is composed mainly of clay minerals or micas, depending upon the degree of metamorphism to which it has been subjected. The original clay minerals in shale turn into micas with increased levels of pressure and heat, but they still form under relatively low temperatures of 150-300°C (302-572°F). Slate often contains a lot of quartz and other minerals such as feldspar, pyrite and hematite in small amounts.
The Maine slate itself is of a very dark-bluish gray colour and a chemical analysis shows 56.42% of this slate consist of SiO₂. When examined under the microscope this slate reveals muscovite and distorted cubes of quartz measuring up to 0.017 by 0.008 millimeter.

Schist is a foliated metamorphic rock, which consists of medium-sized (0.25 to 2 millimeters large) mineral grains that are visible to a naked eye.
The structure of the minerals present in schist, particularly silicates such as mica and amphiboles, is the key to schistosity: Foliation is usually poorly-developed, or even absent, as schist splits into thin flakes rather than layers.
Temperatures between 300 and 450°C (570 and 840 °F) and pressures of 1 to 4 kilobars are typical.
The Virginian schist is a greenish gray talc-schist: it has a greasy feel and represents a lower grade metamorphosis compared to mica schist, which has coarser grains. However, the grains are visible.
 

Logging requirements

All of the following are required to claim a find. Send your answers within 3 days of logging the cache and include the photo with your log. If I do not receive your answers, I will reach out to you. Should you fail to provide the answers following my request, your log will be deleted.

Requirement 1: Judging simply from looking at the stone map, which US state would you say is geologically most diverse and why? Explain your thoughts.

Requirement 2: Is slate a descendant of schist, or the other way around?

Requirement 3: Locate the states Colorado and Kentucky.
a) If you didn't know anything about geology, would you expect these stones are somehow related? (Do they look similar? What can you say about the structure and colour?)
b) Explain how they are related, based on what you learned about minerals.

Requirement 4: Find Maine and Virginia.
a) Describe the structure and colour of the stones. Do the look similar or not?
b) How are the stones related, if at all? Explain your thoughts.

Requirement 5: Take a photo of yourself/your gpsr/personal object with the Stone Map, if you'd like, pick your home/favourite state. Attach this photo to your log.

I hope you enjoyed the cache and am looking forward to your adventure log :)

Sources:
Star-Spangled Banner House Museum
Baltimore Sun
mineralogy.com
geology.com

- This Earth cache was created with kind permission of the Star-Spangled Banner Flag House -