The type of sediment that consists primarily of mineral grains eroded from rocks on land is called terrigenous sediment.

Here's why:

* Terrigenous means "derived from the land."

* Sediment refers to loose, unconsolidated material that has been transported and deposited by natural processes.

* The mineral grains in terrigenous sediment are often fragments of rocks like granite, sandstone, or basalt. These fragments can be quite varied in size, ranging from large boulders to tiny clay particles.

Here are some examples of terrigenous sediments:

* Sand: Made up of sand-sized grains of quartz, feldspar, and other minerals.

* Clay: Composed of very fine-grained clay minerals.

* Silt: Contains intermediate-sized particles between sand and clay.

* Conglomerate: A sedimentary rock formed from large, rounded pebbles and cobbles.

* Brecia: A sedimentary rock formed from angular fragments of rock.

So, next time you see sand on a beach or a riverbed, remember it's a product of the weathering and erosion of rocks on land!