City Hall – Richmond Virginia
A diverse use of contrasting rock types can be seen starting at the west corner of
1. Walk between the planters with trees and the building. How many different types
of rocks are visible here?
2. Kneel down and examine the rock beneath your feet. Of what mineral(s) is it
3. What is the name of this rock?
Next, move to the dark colored rock forming the lower course of the City Hall.
Study this rock carefully.
1. Of what mineral is this rock composed?
2. How does the rock differ in mineralogy, texture, and surface appearance from the
rock on which you are standing?
3. Are there any signs that this rock is weathering? (Hint: press against the small
brownish spots with your fingernail)
4. Of what mineral is the brown substance composed and from what could it come?
Proceed to the Broad Street entrance to City Hall. Study the white to light gray
rock on either side of the entryway. Do not scratch or drop an acid on this stone
because it is soft (H-3) and effervesces in dilute acid solution.
1. What is the name of this rock?
2. From what rock and how is this rock formed?
3. Is this rock highly, moderately, or slightly metamorphosed?
Enter City Hall through the double doors and stop in front of the large planter in
1. How many different rocks do you see from this vantage point?
The tan and black rocks were formed in strikingly different marine environments.
Study each rock carefully. DO NOT SCRATCH!!
2. Of what mineral is the tan rock composed? (Hint: It will fizz in dilute hydrochloric
acid and has a hardness of three.)
3. What color is the sediment and what does this color suggest about the possible
level of oxygen in the ancient environment?
4. Describe the probable environment of deposition of the tan rock based upon its
mineral content, color, and fauna.
5. What percentage of the rock is composed of fossils?
6. What is the name of this rock?
Move to the pillars covered with the black rock.
1. Of what mineral is this rock composed? (Hint: It has a hardness of three and will
effervesce in dilute hydrochloric acid.)
2. What kind of rock is it?
3. What other mineral(s) occurs as small flecks and blobs in the rock?
4. What mineral or substance could impart a black or dark color to the rocks?
5. What conditions are necessary for the formation of the mineral or substance in the
6. Why would you expect to find few fossils in this kind of rock?
7. Is this rock fossiliferous?
8. Was the rock originally sand or a mud?
9. Would sediment of this size have accumulated in a turbulent or quiet water
11. Describe the probable environment of deposition of the black rock based upon
your observation on the mineral content, grain size, color, and fauna in the rock.
Compare and contrast the tan and black rocks:
Environment of deposition