Question
Mineral Hardness Test Experiment: Using the Mohs Scale to Determine the Hardness of Minerals
Mineral Hardness Test Experiment: Using the Mohs Scale to Determine the Hardness of Minerals
Mineral Hardness Test Experiment: Using the Mohs Scale to Determine the Hardness of Minerals
Introduction
A mineral is a naturally occurring, homogeneous1 inorganic2 solid substance with a definite chemical composition and characteristic crystalline structure, color, and hardness. Minerals are made of particles that bond together. The particles may be hard or soft. This property determines whether the mineral is hard like granite or soft like the graphite in a pencil. In 1812, an Austrian mineralogist named Friedrich Mohs developed a scale for measuring the hardness of minerals. Mohs gathered ten commonly available minerals and scratched them against each other. This allowed him to arrange them on a scale of relative hardness from 1 - 10. The softest minerals were those that were most easily scratched, and they were given a score of 1. The hardest minerals were given a higher score -- closer to 10. Talc was the softest mineral on the scale because every other mineral Mohs tested would leave a mark on it. He gave it a rating of one. Mohs gave a mineral called feldspar a rating of six. That means it was harder and able to scratch all the minerals with lower ratings, but it was softer and could not leave marks on the minerals with higher ratings. A diamond was the hardest of the minerals Mohs tested. It could scratch all the other minerals in the scale, but no other mineral could leave a mark on the diamond.
Today, the Mohs hardness test involves scratching a mineral with an object of known hardness to see if it leaves a mark. A person can use objects of known hardness, such as a fingernail which has a score of 2.5 on the Mohs scale, a penny with a score of 3.5, glass with a score of 5.5, or a steel file at 5.1. In this experiment, the student will use these objects of known hardness to scratch unknown minerals. Then students will draw conclusions about each mineral's identity based on the results.
Purpose
The purpose of this experiment is to determine the identity of unknown minerals by using the Mohs hardness scale. The experiment will involve testing 4 unknown specimens by scratching them with objects of known hardness and using the Mohs scale to determine which minerals the specimens are.
Materials
penny
wire nail
steel file
safety gloves
magnifying glass
flat sheet of glass with smooth edges
4 different unknown mineral specimens (numbered 1 through 4)
Procedure
Use the magnifying glass to observe each unknown mineral and record a description of their physical characteristics in Column 2 of the Data Table.
Try to scratch mineral #1 with a fingernail. If a fingernail did not scratch mineral #1, put on the safety gloves and try to scratch mineral #1 with each of the following objects in this order: penny, wire nail, steel file, and glass.
Record which object(s) scratched mineral #1 or which objects mineral #1 was able to scratch, in Column 3 of the Data Table. (Use the magnifying glass to view scratch if needed.)
Using the data collected in Columns 2 and 3, determine the approximate hardness of mineral #1 in Column 4 of the Data Table.
Compare the appearance of mineral #1 to that shown in the Mohs Hardness Scale Table and record the identity in Column 5 of the Data Table.
Repeat steps 2 through 5 for each of the three remaining unknown minerals.
Results
Analysis
Unknown mineral specimens could be identified by comparing physical descriptions and completing scratch tests to assign hardness scores. Mineral #1 the softest, while Mineral #2 was the hardest.
1homogeneous: of the same or similar nature or kind
2inorganic: not involving living organisms
"Mineral Hardness Test Experiment: Using the Mohs Scale to Determine the Hardness of Minerals" property of Pearson.
Based on the Introduction and the Mohs Hardness Scale, why does feldspar have a higher number score than calcite?
Feldspar is able to scratch calcite.
Calcite and feldspar can both be scratched by a penny.
Feldspar can be scratched by a steel file, but calcite can not.
Calcite is able to scratch all minerals that feldspar can scratch.
Mineral Hardness Test Experiment: Using the Mohs Scale to Determine the Hardness of Minerals
Mineral Hardness Test Experiment: Using the Mohs Scale to Determine the Hardness of Minerals
Introduction
A mineral is a naturally occurring, homogeneous1 inorganic2 solid substance with a definite chemical composition and characteristic crystalline structure, color, and hardness. Minerals are made of particles that bond together. The particles may be hard or soft. This property determines whether the mineral is hard like granite or soft like the graphite in a pencil. In 1812, an Austrian mineralogist named Friedrich Mohs developed a scale for measuring the hardness of minerals. Mohs gathered ten commonly available minerals and scratched them against each other. This allowed him to arrange them on a scale of relative hardness from 1 - 10. The softest minerals were those that were most easily scratched, and they were given a score of 1. The hardest minerals were given a higher score -- closer to 10. Talc was the softest mineral on the scale because every other mineral Mohs tested would leave a mark on it. He gave it a rating of one. Mohs gave a mineral called feldspar a rating of six. That means it was harder and able to scratch all the minerals with lower ratings, but it was softer and could not leave marks on the minerals with higher ratings. A diamond was the hardest of the minerals Mohs tested. It could scratch all the other minerals in the scale, but no other mineral could leave a mark on the diamond.
Today, the Mohs hardness test involves scratching a mineral with an object of known hardness to see if it leaves a mark. A person can use objects of known hardness, such as a fingernail which has a score of 2.5 on the Mohs scale, a penny with a score of 3.5, glass with a score of 5.5, or a steel file at 5.1. In this experiment, the student will use these objects of known hardness to scratch unknown minerals. Then students will draw conclusions about each mineral's identity based on the results.
Purpose
The purpose of this experiment is to determine the identity of unknown minerals by using the Mohs hardness scale. The experiment will involve testing 4 unknown specimens by scratching them with objects of known hardness and using the Mohs scale to determine which minerals the specimens are.
Materials
penny
wire nail
steel file
safety gloves
magnifying glass
flat sheet of glass with smooth edges
4 different unknown mineral specimens (numbered 1 through 4)
Procedure
Use the magnifying glass to observe each unknown mineral and record a description of their physical characteristics in Column 2 of the Data Table.
Try to scratch mineral #1 with a fingernail. If a fingernail did not scratch mineral #1, put on the safety gloves and try to scratch mineral #1 with each of the following objects in this order: penny, wire nail, steel file, and glass.
Record which object(s) scratched mineral #1 or which objects mineral #1 was able to scratch, in Column 3 of the Data Table. (Use the magnifying glass to view scratch if needed.)
Using the data collected in Columns 2 and 3, determine the approximate hardness of mineral #1 in Column 4 of the Data Table.
Compare the appearance of mineral #1 to that shown in the Mohs Hardness Scale Table and record the identity in Column 5 of the Data Table.
Repeat steps 2 through 5 for each of the three remaining unknown minerals.
Results
Analysis
Unknown mineral specimens could be identified by comparing physical descriptions and completing scratch tests to assign hardness scores. Mineral #1 the softest, while Mineral #2 was the hardest.
1homogeneous: of the same or similar nature or kind
2inorganic: not involving living organisms
"Mineral Hardness Test Experiment: Using the Mohs Scale to Determine the Hardness of Minerals" property of Pearson.
Based on the Introduction and the Mohs Hardness Scale, why does feldspar have a higher number score than calcite?
Feldspar is able to scratch calcite.
Calcite and feldspar can both be scratched by a penny.
Feldspar can be scratched by a steel file, but calcite can not.
Calcite is able to scratch all minerals that feldspar can scratch.
Answers
GPT-4o mini
Based on the information provided in the introduction regarding the Mohs Hardness Scale, the correct explanation for why feldspar has a higher number score than calcite is:
**Feldspar is able to scratch calcite.**
In the Mohs scale, a higher number indicates a hardness that can scratch lower-numbered minerals. Feldspar is rated at 6, while calcite is rated at 3. This means that feldspar can scratch calcite, establishing its greater hardness in comparison to calcite. The other options are incorrect for the following reasons:
- **Calcite and feldspar can both be scratched by a penny.** This statement doesn't substantiate the relative hardness; both minerals cannot scratch the penny (which is between 3 to 4 on the Mohs scale), making it irrelevant.
- **Feldspar can be scratched by a steel file, but calcite cannot.** This statement is incorrect because feldspar (6) cannot be scratched by a steel file (5.5) according to the Mohs scale.
- **Calcite is able to scratch all minerals that feldspar can scratch.** This statement is incorrect because since feldspar is harder than calcite, it cannot be true that calcite scratches all of feldspar's scratches.
Thus, the relationship established by the scratch test upholds the conclusions drawn in the Mohs scale, demonstrating the relative hardness of the minerals.
**Feldspar is able to scratch calcite.**
In the Mohs scale, a higher number indicates a hardness that can scratch lower-numbered minerals. Feldspar is rated at 6, while calcite is rated at 3. This means that feldspar can scratch calcite, establishing its greater hardness in comparison to calcite. The other options are incorrect for the following reasons:
- **Calcite and feldspar can both be scratched by a penny.** This statement doesn't substantiate the relative hardness; both minerals cannot scratch the penny (which is between 3 to 4 on the Mohs scale), making it irrelevant.
- **Feldspar can be scratched by a steel file, but calcite cannot.** This statement is incorrect because feldspar (6) cannot be scratched by a steel file (5.5) according to the Mohs scale.
- **Calcite is able to scratch all minerals that feldspar can scratch.** This statement is incorrect because since feldspar is harder than calcite, it cannot be true that calcite scratches all of feldspar's scratches.
Thus, the relationship established by the scratch test upholds the conclusions drawn in the Mohs scale, demonstrating the relative hardness of the minerals.