Tuff: rock bedded in layers that is formed from the deposition of materials associated with volcanic eruptions.
Pumice stone: white glass rock with spongy texture caused by the large number of gas bubbles. It floats.
Diatomite: light-coloured porous rock consisting almost exclusively of microscopic single-cell marine organisms with a silica shell.
Rhyolite: light-coloured acidic volcanic rock of silica-rich composition (SiO2 > 68 %).
Dacite: light-coloured volcanic rock with a high silica content (SiO2 = 63-68 %).
Andesite: volcanic rock that is intermediate in composition between dacite and basalt, containing silica SiO2 = 56-63 %.
Andesitic lava: lava containing andesite.
Pyroclastic materials: unconnected fragments of magma rocks that are ejected violently during a volcanic eruption.
Volcanic breccia: compact rocks composed of various angular fragments of volcanic rock.
Volcanic fireballs: pieces of lava that are ejected into the air after a volcanic eruption and adopt an aerodynamic curved shape that they retain when cooled.
Clay minerals: minerals consisting of successive layers of microscopic sheets, with interlayers that have absorbed water, cations (i.e. kaolinite).
Iron oxides: iron oxide-hydroxide compounds that form minerals, such as limonite and hematite, with yellow, red and brown colours.
Hydrothermal deposits: sedimentation, mainly of metals (Fe, Mn, Cu), originating from hot solutions (100-400ο C) after magma crystallisation.
Hydrothermal solutions: the circulating hot water-based solutions (100-400ο C ) that are formed after magma crystallisation and contain various metals that are mostly deposited into cracks.
Psammitic tuff: rock composed of volcanic materials deposited in a silica-rich sedimentary environment (i.e. sea sand).
Manganese dendrites: tree-shaped manganese formations consisting of microscopic branched crystals that are reminiscent of plant imprints.
Lava: molten rock that reaches the earth’s surface in liquid form during a volcanic eruption (700-1200ο C).