Petrified wood
Petrified wood is a popular decorative object.
It also helps to ground oneself, if one tends to lose oneself in thoughts.
For meditation, a disc is suitable to sit on.
Depending on whether the wood substance was replaced by quartz or opal,
one speaks accordingly of quartzized or opalescent wood.
Petrified wood can only be formed when the wood is covered by sediment
was cut off from oxygen very quickly. Otherwise the wood would rot.
Petrified wood can occur worldwide, significant deposits are
in the USA, Brazil, Australia and Madagascar