The Geological Society of London’s Online interactive resource The Rock Cycle, with the Rock Cycle Animation, shows how surface and deep Earth processes produce the rocks we stand on and use to build our homes. Also find a glossary, demonstrations/experiments and extensive background information about the rock cycle.
Observe the interesting optical effects schiller, iridescence, pleochroism, and alexandrite effect.
Test objects to determine which minerals, rocks, and other materials are naturally magnetic.
Break minerals to observe their cleavage or fracture. How a mineral breaks depends upon the mineral’s structure. Cleavage is an easily demonstrated property of minerals such as calcite, halite, and mica.
Students take a small piece of unexpanded vermiculite, holding it with tongs or long tweezers, and insert it into the ﬂame of a propane torch. The vermiculite expands rapidly to many times its original thickness.
Exposure to ultraviolet light causes changes in minerals. One of the lesser-known phenomena is tenebrescence, in which a mineral actually changes color upon exposure to ultraviolet light (this is not the same as ﬂuorescence). Using an ultraviolet light, you can give a mineral a reversible “suntan.”
Everyone loves ﬁreworks and students often wonder how ﬁreworks get their rich colors. Using the flame test, students can produce their own colored flames and learn about ﬁreworks, minerals, and their common elements.
Rank samples as harder or softer by scratching them with your fingernails. Once the specimens are ranked by hardness, test that softer ones cannot scratch harder ones.
On the Mohs Hardness Scale, talc or soapstone has a Mohs hardness of 1 and is even softer than your skin. Your fingernail can scratch gypsum, which has a hardness of 2, but not calcite, with a hardness of 3. Your fingernail thus has a hardness of about 2.5.
Experience differences in the density of rocks and minerals first-hand by hefting samples of pumice and scoria and guessing if they are heavier or lighter than water. Then simply drop the specimens into a tank of water to test if they will ﬂoat.
Detect differences in minerals and rocks using your sense of smell. When you scratch a rock or mineral, a smell can indicate the presence of tiny invisible ﬂuid inclusions and give clues to composition.