* Fracture describes how a mineral breaks along irregular surfaces. This is a reliable characteristic.

* Streak refers to the color of a mineral's powder when rubbed against a streak plate. This is a more consistent identifier than the overall color of the mineral.

* Softness is measured on the Mohs Hardness Scale, which compares a mineral's resistance to scratching. This is a fundamental property.

Color can be misleading because:

* Many minerals come in a variety of colors due to impurities or variations in their chemical composition.

* The same mineral can appear different colors depending on the lighting conditions.

Therefore, color is a less reliable indicator of mineral identity compared to the other options.