Rocks and Minerals by UTH Rocks and Minerals by UTH    

Lesson 24: Geodes

Directions

Study the lesson for one week.

Over the week:

• Read the lesson.
• Review the synopsis.
• Recite aloud the vocabulary words and their definitions.
• Study the rock and mineral of the week.
• Complete the enrichment activities.
• Study the review questions.

Synopsis

Geodes are rounded rocks hiding beautiful crystals within. Geodes form either as igneous rocks from bubbles in volcanic rock or as sedimentary rocks when water dissolves a cavity in a rock.

Vocabulary

Geode: A nodule of stone having a cavity lined with mineral or crystal matter on the inside wall.
Igneous Rock: A rock formed by the cooling of molten rock, either below the surface (intrusive) or on the surface (extrusive).
Sedimentary Rock: A rock formed by the deposition of either the weathered remains of other rocks, the results of biological activity, or precipitation from solution.

Rock or Mineral of the Week

• Amethyst crystals are sometimes found in geodes.

• Amethyst is a transparent purple variety of quartz (SiO2) that is used as a gemstone.
• The color of amethyst comes from trace amounts of other elements such as iron (Fe) and manganese (Mn).

Physical Characteristics

• Color: Shades of purple
• Hardness: 7
• Luster: Vitreous
• Cleavage: None
• Streak: White
• Tenacity: Brittle

Location

• Especially large deposits in Brazil and Uruguay

Interesting Facts

• The name 'amethyst' is Greek for intoxicate, as it was once believed amethyst protected the wearer from alcohol intoxication.

• Amethyst is the birthstone for those born in February.

Enrichment

Activity 1: Narrate the Lesson

• After reading or listening to the lesson, narrate the lesson aloud using your own words.

Activity 2: Can You Find It?

Find the following elements on the periodic table:

• Silicon (Si)
• Oxygen (O)
• Iron (Fe)
• Manganese (Mn)
• In which group and period is manganese (Mn)?

Activity 3: Map the Lesson

• Large deposits of amethyst are found in Brazil and Uruguay.
• Find Brazil and Uruguay on the map of South America.

Activity 4: Take a Nature Walk

• Embark on a nature walk.
• Collect one rock or mineral specimen.
• Use the gathered specimen to create the field book entry.

Activity 5: Complete a Field Book Entry   

After your nature walk, complete page 6 in 'Fifth Grade Science Rocks and Minerals Notebook Pages.'

Review

Question 1

Describe something about geodes.

1 / 5

Answer 1

Geodes are hollow rocks lined with crystal matter on the inside wall.

1 / 5

Question 2

Are geodes igneous, metamorphic, and/or sedimentary rocks?

2 / 5

Answer 2

Geodes are either igneous or sedimentary rocks.

2 / 5

Question 3

Is amethyst (SiO2 + Fe/Mn) a compound?

3 / 5

Answer 3

Yes, amethyst (SiO2 + Fe/Mn) is a compound consisting of multiple types of elements.

3 / 5

Question 4

How many different elements does amethyst (SiO2 + Fe/Mn) contain?

4 / 5

Answer 4

Amethyst (SiO2 + Fe/Mn) contains two types of elements - Silicon (Si) and Oxygen (O) plus additional trace elements (either iron (Fe) or manganese (Mn)).

4 / 5

Question 5

What gives amethyst (SiO2 + Fe/Mn) its beautiful purple color?

5 / 5

Answer 5

Trace amounts of iron (Fe) or manganese (Mn) gives amethyst its beautiful purple color.

5 / 5

❮ ❯

1. Describe something about geodes. Geodes are hollow rocks lined with crystal matter on the inside wall.
2. Are geodes igneous, metamorphic, and/or sedimentary rocks? Geodes are either igneous or sedimentary rocks.
3. Is amethyst (SiO2 + Fe/Mn) a compound? Yes, amethyst (SiO2 + Fe/Mn) is a compound consisting of multiple types of elements.
4. How many different elements does amethyst (SiO2 + Fe/Mn) contain? Amethyst (SiO2 + Fe/Mn) contains two types of elements - Silicon (Si) and Oxygen (O) plus additional trace elements (either iron (Fe) or manganese (Mn)).
5. What gives amethyst (SiO2 + Fe/Mn) its beautiful purple color? Trace amounts of iron (Fe) or manganese (Mn) gives amethyst its beautiful purple color.

References

'Geode.' Wikipedia. en.wikipedia.org/wiki/Geode. n.p.

'Amethyst.' Wikipedia. en.wikipedia.org/wiki/Amethyst. n.p.

Cited Physical Properties. Geology.com. geology.com/rocks. n.p.