Chert

High school (ages 12+)
Environment & Earth

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/chert

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 mineralogical composition?Predominantly microcrystalline or cryptocrystalline quartz (SiO2)
2. What is the primary formation environment?Deep ocean floors from biogenic siliceous ooze
3. How does chert form?Chert forms when tiny marine animals with silica shells die and their shells pile up on the ocean floor. Over millions of years, the shells are packed together and turn into rock.
4. Why did people use chert to make tools?Chert is hard and breaks with a sharp, clean edge. Early humans could shape it into knives, arrowheads, and other tools that helped them survive.

Cryptocrystalline: Composed of crystals that are too small to be distinguished even with a microscope.
Diagenesis: The physical and chemical changes occurring in sediment after deposition and before metamorphism.
Siliceous Ooze: A deep-sea sediment composed primarily of the silica skeletons of microorganisms.
Precambrian: The earliest eon of Earth's history, before the Phanerozoic Eon (before about 541 million years ago).