An igneous rock forms quickly. Which characteristics could the rock have?
A. Evidence of holding
B. Smooth, sharp texture
C. Small sand grains
D. Large mineral crystals
D. Large mineral crystals
An igneous rock forms when molten magma cools and solidifies quickly. Based on this information, the characteristics that an igneous rock formed quickly could have are:
A. Evidence of holding: This characteristic is not directly related to the speed at which the rock forms. It refers to the presence of vesicles (bubbles) or small cavities within the rock.
B. Smooth, sharp texture: This characteristic is not typically associated with igneous rocks that form quickly. Rapid cooling often results in a fine-grained texture.
C. Small sand grains: This characteristic is not typically associated with igneous rocks that form quickly. Rapid cooling often prevents the growth of large mineral grains, resulting in a fine-grained or glassy texture.
D. Large mineral crystals: This is not typically a characteristic of igneous rocks formed quickly. Slow cooling allows more time for mineral crystals to grow, resulting in larger crystal size. Rapid cooling inhibits crystal growth, leading to smaller crystals or a glassy texture.
Therefore, the correct answer is B. Smooth, sharp texture.
To determine which characteristics an igneous rock that forms quickly could have, we'll break down each answer option:
A. Evidence of holding: This choice doesn't directly relate to the characteristics of igneous rocks that form quickly. The term "holding" is vague and unclear in the context of rock formation.
B. Smooth, sharp texture: This choice is unlikely for quickly forming igneous rocks. Rocks formed quickly often lack time for the development of smooth or sharp textures, which require more prolonged cooling and/or weathering processes.
C. Small sand grains: This choice is more in line with the characteristics of igneous rocks that form quickly. These rocks, known as volcanic rocks, can be formed from rapid cooling of magma or lava. The resulting texture is usually fine-grained or even glassy if the cooling is extremely quick.
D. Large mineral crystals: This choice is unlikely for igneous rocks that form quickly. Large mineral crystals typically require a longer cooling period, allowing enough time for the growth of mineral grains.
Based on these explanations, the correct answer is C. Small sand grains for igneous rocks that form quickly.