Obsidian gives conchoidal fractures

Conchoidal fracture describes the way that brittle materials break when they do not follow any natural planes of separation. Obsidian is a naturally occurring Glass formed as an extrusive Igneous rock. A fracture is the (local separation of an object or material into two or more pieces under the action of stress. Cleavage, in Mineralogy, is the tendency of crystalline materials to split along definite planes creating smooth surfaces of which there are several named types Materials that break in this way include flint and other fine-grained minerals, as well as most amorphous solids, such as obsidian and other types of glass. Flint (or flintstone) is a hard sedimentary Cryptocrystalline form of the Mineral Quartz, categorized as a variety of Chert A crystallite is a domain of solid-state matter that has the same structure as a single Crystal. A mineral is a naturally occurring substance formed through geological processes that has a characteristic chemical composition a highly ordered atomic structure and specific An amorphous solid is a Solid in which there is no Long-range order of the positions of the Atoms (Solids in which there is long-range atomic order are Obsidian is a naturally occurring Glass formed as an extrusive Igneous rock. Glass in the common sense refers to a Hard, Brittle, transparent Solid, such as that used for Windows many

Conchoidal fractures can also occur in other material under favorable circumstances. This material property was widely used in the Stone Age to make sharp tools, and minerals that fractured in this fashion were widely traded as a desirable raw material. The Stone Age is a broad prehistoric time period during which Humans widely used stone for toolmaking

Conchoidal fractures often result in a curved breakage surface that resembles the rippling, gradual curves of a mussel shell; the word "conchoid" is derived from the word for this animal. The common name mussel is used for members of several different families of Clams or Bivalve Molluscs, from both saltwater and freshwater habitats A swelling appears at the point of impact called the bulb of percussion. Shock waves emanating outwards from this point leave their mark on the stone as ripples. Other conchoidal features include small fissures emanating from the bulb of percussion. In Anatomy, fissure ( Latin fissura, Plural fissurae) is a groove natural division deep furrow cleft or tear in various parts of

They are defined in contrast to the faceted fractures often seen in single crystals such as semiconductor wafers and gemstones, and the high-energy ductile fracture surfaces desirable in most structural applications. Facets are flat faces on geometric shapes The organization of naturally occurring facets was key to early developments in Crystallography, since they reflect the underlying In Materials science, a crystal is a Solid in which the constituent Atoms Molecules or Ions are packed in a regularly ordered repeating A wafer is a thin slice of Semiconductor material such as a Silicon crystal used in the fabrication of Integrated circuit and other microdevices A gemstone or gem, also called a precious or semi-precious stone, is a piece of attractive Mineral, which &mdash when cut and polished &mdash Ductility is a mechanical property used to describe the extent to which materials can be deformed plastically or "stretched" into "wires" without See the main article on Fracture. A fracture is the (local separation of an object or material into two or more pieces under the action of stress.

Conchoidal fractures form the basis of flint knapping, since the shape of the broken surface is controlled only by the stresses applied, and not by some preferred orientation of the material. A knapper is a person who shapes Flint, Chert, Obsidian or other stone through the process of knapping or Lithic reduction to manufacture Stress is a measure of the average amount of Force exerted per unit Area. This property also makes such fractures useful in engineering, since they provide a permanent record of the stress state at the time of failure. Failure ( fail, phail or flop) in general refers to the state or Condition of not meeting a desirable or intended objective As conchoidal fractures can be produced only by mechanical impact, rather than frost cracking for example, they can be a useful method of differentiating prehistoric stone tools from natural stones. Frost is the solid deposition of Water vapor from saturated air

Conchoidal fracture in art

Conchoidal fracture in glass

Conchoidal fracture as originally developed by prehistoric men is used by highly skilled artists to craft bifacial glass pieces for ornamental, as well as functional enlightened sculptures.