Rocks and Minerals by UTH Rocks and Minerals by UTH    

Lesson 7: Physical Properties: Hardness

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

Rocks and minerals may be identified by one or more of their physical properties. An additional identifying physical property of rocks and minerals is hardness. Hardness is defined as the resistance to scratching, cutting, indentation, or abrasion of a metal or other solid material. When it comes to minerals, scientists use Mohs scale to measure hardness. Mohs Scale is a comparative scale of the hardness of minerals based on their ability to scratch one another. Mohs scale ranges from 1.0 (softest) to 10.0 (hardest).

Vocabulary

Physical Property: Characteristics of matter not involving a change in chemical composition.
Hardness: The resistance to scratching, cutting, indentation, or abrasion of a metal or other solid material.
Mohs Scale: A comparative scale of the hardness of minerals based on their ability to scratch one another.
Alps: A mountain range in Western Europe, running from France to Slovenia, with its highest peak Mont Blanc at 4808 meters.
Himalayas: The mountain range in south-central Asia which extends about 2,414 km (1,500 mi) through Kashmir, northern India, southern Tibet, Nepal, Sikkim, Bhutan and Assam; it contains nine of the world’s ten highest peaks, including Mount Everest/Qomolongma.
Vitreous: Of or resembling glass.
Sectile: Capable of being cut smoothly with a knife.

Rock or Mineral of the Week

Overview

• Talc is a soft clay mineral that can be scratched with a fingernail.
• Talc is one of the softest minerals and is assigned a value of 1 on Mohs scale.

Physical Characteristics

• Color: Whitish, gray, green
• Hardness: 1
• Luster: Vitreous and Pearly
• Cleavage: Yes
• Streak: White
• Tenacity: Sectile (capable of being cut smoothly with a knife)

Locations

• The United States, the Alps, the Himalayas, and additional locations

Interesting Facts

• Talc was once widely used in baby powder.

• However, questions of its safety and numerous lawsuits led companies to remove talc from many baby powder formulations.

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:

• Magnesium (Mg)
• Silicon (Si)
• Oxygen (O)
• Hydrogen (H)
• In which group and period is Magnesium (Mg)?

Activity 3: Map the Lesson

• Talc is found in the Alps and Himalayas mountain ranges.
• The Alps are a mountain range ranging across eight countries in Europe. Find France, Switzerland, Monaco, Italy, Liechtenstein, Austria, Germany, and Slovenia on the map of Europe.

• The Himalayas are a mountain range in Asia, stretching over five countries. Find Bhutan, China, India, Nepal and Pakistan on the map of Asia.

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

Is hardness a physical property or a chemical property?

1 / 4

Answer 1

Hardness is a physical property, for it does not involve a change in chemical composition.

1 / 4

Question 2

Describe something about talc.

2 / 4

Answer 2

Talc is a soft clay mineral ranging in color from whitish to green with a hardness of 1.0 on Mohs scale.

2 / 4

Question 3

Is talc (Mg3Si4O10(OH)2) a compound?

3 / 4

Answer 3

Yes, talc (Mg3Si4O10(OH)2) is a compound containing more than one type of element.

3 / 4

Question 4

How many different elements does talc (Mg3Si4O10(OH)2) contain?

4 / 4

Answer 4

Talc (Mg3Si4O10(OH)2) contains four types of elements - Magnesium (Mg), Silicon (Si), Oxygen (O), and Hydrogen (H).

4 / 4

❮ ❯

1. Is hardness a physical property or a chemical property? Hardness is a physical property, for it does not involve a change in chemical composition.
2. Describe something about talc. Talc is a soft clay mineral ranging in color from whitish to green with a hardness of 1.0 on Mohs scale.
3. Is talc (Mg3Si4O10(OH)2) a compound? Yes, talc (Mg3Si4O10(OH)2) is a compound containing more than one type of element.
4. How many different elements does talc (Mg3Si4O10(OH)2) contain? Talc (Mg3Si4O10(OH)2) contains four types of elements - Magnesium (Mg), Silicon (Si), Oxygen (O), and Hydrogen (H).

References

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

'Mohs scale of mineral hardness.' Wikipedia. en.wikipedia.org/wiki/Mohs_scale_of_mineral_hardness. n.p.

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