Sedimentary and Metamorphic Rocks - Rock Cards

Geology enthusiasts and students alike can explore the fascinating world of rocks with this collection of rock cards, which describe various sedimentary, metamorphic, and igneous rocks. Conglomerate, for instance, is a coarse-grained sedimentary rock characterised by its rounded grains. Sandstone, another sedimentary rock, is primarily composed of sand-sized particles and often found in distinct layers. Shale, with its very fine grains, is also sedimentary, while coal, derived from carbonized plant matter, has been a crucial material throughout human history. Chalk and limestone, both sedimentary rocks made of calcium carbonate, are noted for their softness and susceptibility to weathering, with limestone also serving as the precursor to marble, a metamorphic rock favoured for sculpture. Mudstone, also sedimentary, originates from clay and mud.

In contrast, slate is a fine-grained metamorphic rock that evolves from shale or silt, and schist is recognised by its banded appearance. Gneiss, commonly found in regions like New England and the Rocky Mountains, is another metamorphic rock, as is hornfels, which forms when shale or mudstone is baked by nearby igneous rock. Novaculite, a dense metamorphic rock found in the US and Japan, results from marine remains and quartz under extreme conditions, while phyllite is mostly made of mica. Migmatite uniquely blends metamorphic and igneous characteristics. Among igneous rocks, diorite and gabbro are composed mainly of feldspar and are coarsely grained, while granite is known for its hardness. Hornblende forms deep underground, and obsidian is a glassy volcanic rock that cools rapidly. Pumice, with its low density and bubbly structure, is a product of cooling volcanic material, just like tuff, which is composed of volcanic ash, and rhyolite, with its high silica content, completes this comprehensive overview of rock types.