Accretionary Lapilli Tuff
£1.00 – £2.74
Accretionary lapilli tuff, formed from volcanic material in the air mixing with moisture and falling on to material below, creating a birds eye feature on the rock, specimens are from Cumbria and are available in optional sizes, supplied in a card tray with an information label.
Lapilli tuff is an pyroclastic igneous rock which is often formed when material produced by the volcanic activity falls out of the air, although it can also be used to describe similar material which has been ejected and falls from the air during meteorite impacts as well, it is seen as more of a size distinction, with material between 2 - 64 mm being being lapilli, anything less is referred to as ash and anything greater volcanic bombs or blocks. These particular specimens how ever also exhibit an accretionary feature which is sometimes known as 'birds eyes'. They appear as numerous elongated glassy dots on the surface of the specimens and are formed when volcanic particles in an ash cloud mix with moisture in the air which eventually form a sort of hailstone, composed mostly of ash and volcanic material, held together by moisture. As the particles get heavier, they fall downward onto the material below, creating a dotted feature on the rock. These rock specimens come from Longsleddle, Cumbria and are supplied in various sizes which you can choose from, and will come in a card tray with an information label.