The pore spaces (known as vesicles) in pumice are a clue to how it forms. The vesicles are actually gas bubbles that were trapped in the rock during the rapid cooling of a gas-rich frothy magma. The material cools so quickly that atoms in the melt are not able to arrange themselves into a crystalline structure.umice is produced in two forms: rock pumice and pumicite. Pumicite is a name given to very fine grained pumice (less than 4 millimeters in diameter down to submillimeter sizes).
Post and lintel construction is recognized by its simple vertical and horizontal design, in which a pair of vertical supports are set in the ground or a foundation, and a horizontal structure is balanced on top of them.
The design printed above, the Circle of Perfection of Ancient Craft Masonry, portrays graphically the course of advancement which experience has shown to be the best and wisest for the young Mason to follow, namely: through the Royal Arch Chapter, and the Cryptic Council.