Prehistoric tools included spears with chipped stone tips for a sharper edge.
Obsidian is a black glassy substance formed when lava cools in a short period of time. Due to the rapid rate of cooling, very few crystals can form in the material. This makes obsidian an essentially natural glass and has been shown to be useful due to the lack of crystals. In particular, it can be cut to have very sharp edges. It was a preferred material for weapons during the Stone Age and is still used in some surgical instruments today.
When lava cools in a short period of time, obsidian is formed.
Obsidian is not difficult to recognize. It is often black in color and, even in its unpolished form, is often quite shiny. It’s made of about 70% silicon dioxide or more, which explains its color. However, if obsidian mixes with some minerals, it can take on other colors. For example, a high level of iron or magnesium can cause the rock to appear dark green instead of black. Some have a snowflake pattern that results from the formation of cristobalite on top.
In other cases, the substance bubbles and forms in layers. This can create a rainbow or golden obsidian. These two variants are harder to find in large numbers.
Scalpels are usually made of obsidian.
Obsidian is not really a mineral or a rock, because it does not contain crystalline structures. Some refer to it as a mineraloid. A mineraloid is a mineral-like substance that lacks crystalline structures. Other examples of mineraloids include opals and pearls.
It is a relatively soft substance, with only a rating of around 5 to 5.5 on the Mohs scale. However, despite its softness, it was the preferred material for making weapons as it could be refined to have a very sharp blade. You can still find arrowheads all over North America made of obsidian. It can also be used for decorative purposes. Easter Island stone statues are made of this material.
Surgeons often use scalpels and surgical knives made of obsidian.
Some surgeons, particularly the cardiothoracic surgeon, use obsidian scalpels and surgical knives. The sharper the knife can be, the less damage it does to fabrics when cutting. These special surgical cutting instruments often shorten healing time due to their sharpness.
Obsidian can be found in many places on Earth, especially in areas such as quarries or where there has been volcanic activity. However, it deteriorates into tiny glass crystals over time. There are no examples prior to the Cretaceous period, 145 to 400 million years ago.