Final answer:
Quartz and olivine are minerals not likely to be found together in igneous rocks because of their distinct formation conditions. Quartz is common in felsic rocks, while olivine is typical in mafic to ultramafic rocks. Geologists use mineral associations and rock color to help classify and identify different types of igneous rocks. The correct option is d.
Step-by-step explanation:
The minerals likely not to be found together in igneous rocks are quartz and olivine. This is due to their different formation conditions and chemical compositions. Quartz is a silica-rich mineral typically found in felsic rocks such as granite or rhyolite, which have high silica content and are lighter in color. Olivine, on the other hand, is commonly found in ultramafic to mafic rocks like peridotite or basalt, which are darker due to their higher iron and magnesium content.
Minerals with similar formation processes and compatible chemistries are more likely to be found together. For instance, pyroxene and olivine can be expected in mafic rocks, while quartz and feldspar are companions in felsic rocks.
The classification of igneous rocks based on color and mineral content helps geologists identify them; dark-colored rocks are typically mafic or ultramafic, while light-colored rocks are usually felsic or silicic. Thus, knowing mineral associations and the rock's color are key factors in identifying the rock's mineralogy.
Hence, Option d is correct.