Final answer:
Graphite is soft, allowing it to leave marks on paper, whereas pyrite is hard and brittle, attributed to their differing crystal structures and bonds. This tactile distinction helps in identifying the correct mineral, aiding geologists and artists alike.
Step-by-step explanation:
The feel of graphite and pyrite can be used to distinguish between these minerals because they have different textures and hardness. Graphite, often used in pencil lead, is soft due to the weak Van der Waals forces between its carbon layers, allowing it to easily rub off onto paper. In contrast, pyrite, often mistaken for gold with its metallic luster, is hard and brittle. This difference in texture and hardness directly relates to the bonding and structural differences within each mineral. While graphite's layers slip past one another due to weak bonding, pyrite's crystal structure has strong ionic bonds between iron and sulfur atoms that result in its greater hardness and distinctly different feel.
Artists appreciate graphite for its softness, as they can choose pencils that produce very dark lines (B) or lighter, grayer lines (HB or H) based on the binder content mixed with the graphite. Conversely, pyrite isn't useful for drawing but does have other applications due to its metallic properties and hardness, such as in the production of sulfur and sulfuric acid.
Identifying such mineral properties is essential for geologists in the field or the classroom, as these properties allow for easier determination of a mineral's identity without costly equipment. Understanding these tactile differences aids in distinguishing between minerals with similar appearance but different properties.