Answer:
It is an extrusive igneous rock
Step-by-step explanation:
Based on the physical appearance, the geologist can make an accurate conclusion about the rock's formation and in which type of rocks does it belong. The fine-grains made up of small crystals give away clues about the formation of the rock. Fine grains with small structures occur when the lava reaches the surface and cools off very quickly, thus not giving the crystals enough time to grow, so they are very small. The geologist can classify this rock on base of this information as an igneous rock, as it has been formed from lava, and as an extrusive igneous rock, as the fine grains and small crystals only occur when the lava cools of quickly on the surface.