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Obsidian (/ ə b ˈ s ɪ d i. ən, ɒ b-/ əb-SID-ee-ən ob-) [5] is a naturally occurring volcanic glass formed when lava extruded from a volcano cools rapidly with minimal crystal growth. It is an igneous rock. [6] Obsidian is produced from felsic lava, rich in the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium.
Because obsidian is not natural to Belize, the site of excavation, the obsidian cores were the product of transactions between the Mayans and those in present-day Honduras, Mexico and Guatemala. Obsidian blades are the sharpest natural cutting edges known, and after the lithic reduction already fractured blades, the triangular heads were produced.
Obsidian is a naturally formed volcanic glass that was an important part of the material culture of Pre-Columbian Mesoamerica. Obsidian was a highly integrated part of daily and ritual life, and its widespread and varied use may be a significant contributor to Mesoamerica's lack of metallurgy.
The most famous and most prevalent prismatic blade material is obsidian, as obsidian use was widespread in Mesoamerica, though chert, flint, and chalcedony blades are not uncommon. The term is generally restricted to Mesoamerican archaeology, although some examples are found in the Old World , for example in a Minoan grave in Crete .
The most common blade materials are carbon steel, stainless steel, tool steel, and alloy steel. Less common materials in blades include cobalt and titanium alloys, ceramic, obsidian, and plastic. The hardness of steel is usually stated as a number on the Rockwell C scale (HRC). The Rockwell scale is a hardness scale based on the resistance to ...
A scalpel, lancet, or bistoury is a small and extremely sharp bladed instrument used for surgery, anatomical dissection, podiatry and various handicrafts. A lancet is a double-edged scalpel. Scalpel blades are usually made of hardened and tempered steel, stainless steel, or high carbon steel; in addition, titanium, ceramic, diamond and even ...
Sharpening stone. An oil stone. Sharpening stones, or whetstones, are used to sharpen the edges of steel tools such as knives through grinding and honing. Such stones come in a wide range of shapes, sizes, and material compositions. They may be flat, for working flat edges, or shaped for more complex edges, such as those associated with some ...
Glass knife. A glass knife is a knife with a blade made of glass, with a fracture line forming an extremely sharp cutting edge. Glass knives were used in antiquity due to their natural sharpness and the ease with which they could be manufactured. In modern electron microscopy glass knives are used to make the ultrathin sections needed for imaging.