Here's why:
* Color is a visual property. You can see it with your eyes without needing any tools or tests.
* Other properties require tests or tools. For example, streak requires rubbing the mineral on a streak plate, hardness requires scratching the mineral with a known hardness object, and luster requires observing how light reflects off the surface.
Important Note: While color is easy to observe, it's not always a reliable indicator of a mineral's identity. Many minerals come in various colors due to impurities or variations in their chemical composition.
