The size of an average sized head
Examples of igneous rocks are pumice, obsidian, basalt, and rhyolite.
obsidian
One word for this is obsidian. Obsidian is a gorgeous hard stone, usually but not always black, and sometimes with iridescent, almost opalescent highlights. Tachylite is also a volcanic glass of basaltic composition.
Making a cutting tool using obsidian rock is quite easy. The cavemen used to smack pieces of obsidian with other rocks until the obsidian was thin and sharp as a knife.
Obsidian is formed from very rapidly cooling lava.
Examples of igneous rocks are pumice, obsidian, basalt, and rhyolite.
Obsidian is black glass formed by volcanoes.
because an obsidian rock has low silica
Igneous rocks
Obsidian
Glassy rocks are rocks that have cooled and solidified quickly, without forming crystals. This rapid cooling prevents mineral crystals from growing, resulting in a smooth and glass-like texture. Obsidian and pumice are examples of glassy rocks.
Very smooth rocks are called "polished rocks" or "river rocks" due to the smooth texture achieved from erosion in water bodies like rivers and oceans.
A while.
oh it rocks! You have to read it
obsidian
One word for this is obsidian. Obsidian is a gorgeous hard stone, usually but not always black, and sometimes with iridescent, almost opalescent highlights. Tachylite is also a volcanic glass of basaltic composition.
Examples of igneous rocks are pumice, obsidian, basalt, and rhyolite.