Explain the 3 textures that are used in identifying igneous rocks?

What type of texture will an igneous rock have if it cools slowly?
I said coarse and grained?

Is the process of dissolved minerals getting deposited into the spaces among larger sediments called sedimentary deposition? I said YES

Why is slate more commonly used as a chalkboard than shale?

shale is generally soft compared to slate and would crumble if used as a chalkboard.

The three textures used in identifying igneous rocks are:

1. Glassy texture: This texture is characteristic of rocks that cool so rapidly that they do not have time to crystallize. As a result, the rock appears smooth and glass-like, similar to obsidian.

2. Porphyritic texture: This texture occurs when an igneous rock undergoes two stages of cooling. The initial slow cooling allows large mineral crystals to form (phenocrysts), while subsequent rapid cooling produces finer-grained matrix material.

3. Fine-grained texture: This texture is typical of rocks that cool quickly, allowing small mineral crystals to form. The individual mineral grains are often not visible to the naked eye.

Regarding the type of texture an igneous rock will have if it cools slowly, you were correct to say coarse-grained. In general, a slower cooling rate allows for larger mineral crystals to form, resulting in a coarser texture. This happens because there is more time for the mineral crystals to grow without being disrupted by rapid cooling.

Now, moving on to the question about sedimentary deposition, no, the process of dissolved minerals getting deposited into the spaces among larger sediments is not called sedimentary deposition. It is called cementation. Cementation is a common process in sedimentary rocks where minerals precipitate and bind the sediments together, forming a solid rock.

Finally, regarding the choice between slate and shale for use as a chalkboard, slate is more commonly used because it has a finer-grained texture and is less prone to breaking or crumbling. Slate is formed from the metamorphism of shale, which involves intense heat and pressure. This process rearranges the minerals and creates a smoother, more durable rock, making it suitable for use as a chalkboard. Shale, on the other hand, has a more layered and brittle composition, making it less ideal for chalkboard use.