Sillar

High school (ages 12+)
Geography

Name:

Date:

Step 1 · Read the article

Open the article and read it at the level above. Then answer the questions below in your own words.

https://smallwhale.org/articles/sillar

Write what each word means, using the article.

Do not copy the article. Write two things you learned, the way you would explain them to a friend.

Answers below are taken from the article’s stored facts, so they match what the student read.

1. What is the geological classification?A variety of rhyolite, often containing andesite fragments
2. What is the formation mechanism?Lithified pyroclastic flow deposits of tuff
3. Why does sillar sometimes look pink and sometimes white?Pink sillar has tiny iron crystals called hematite that give it a rosy tint. White sillar doesn’t have these crystals, so it stays bright and clean.
4. How does sillar form during a volcano eruption?When a volcano blows, hot ash, gas, and rock rush down its sides in a fast flow called a pyroclastic flow. When that flow slows, the material settles and hardens into sillar.

Rhyolite: An extrusive igneous rock, chemically equivalent to granite, characterized by a high silica content.
Andesite: An intermediate volcanic rock, typically gray or dark-colored, with a composition between basalt and rhyolite.
Pyroclastic Flow: A fast-moving current of hot gas and volcanic matter that flows along the ground, typically following a volcanic eruption.
Tuff: A rock composed of consolidated volcanic ash, often containing fragments of other volcanic rocks.