What materials were available in 1620 on the Mayflower? where is the original mayflower ship now.
When examining glass fractures What characteristic helps to determine the direction of the projectile creating the fractures?
Conchoidal fracture It often occurs in amorphous or fine-grained minerals such as flint, opal or obsidian, but may also occur in crystalline minerals such as quartz.
Mindat.org defines conchoidal fracture as follows: “a fracture with smooth, curved surfaces, typically slightly concave, showing concentric undulations resembling the lines of growth of a shell“.
Examples of Conchoidal Fracture Note curved surfaces that are concave into the shell. Manmade glass, knapped. Note the concave scars scooped into the glass, curved in shape. These are termed conchoidal.
Conchoidal fracture is a smoothly curving fracture surface of fine-grained materials which have no planar surfaces of internal weakness or planes of separation (no cleavage). Such a curving fracture surface is characteristic of glass and other brittle materials with no crystal structure.
limestone #1 Originally deposited as microscopic aragonite needles, but now converted to calcite and then calcite cemented to form the rock. See Origin Of Micrite for more details. Dense, uniform, fine grained rock with conchoidal fracture.
Anthracitic coals are high-rank coals. They are shiny (glassy) and break with a conchoidal (glass-like) fracture.
Igneous rocks can be identified by the determination of the composition and texture of the rock. Once these two characteristics have been identified, the Igneous Rock Identification chart is used to identify the rock name.
By double refraction when light passes through calcite, it is split into two rays and is refracted twice. I would suggest to take a piece of paper and make a point with pencil, then place the calcite mineral on top of the point and see whether the point splits into two or not. If it does then it is calcite.
Conchoidal (shell-like) fracture patterns in the glass are the result of stress on the glass and breakage due to application of a force. The two types of conchoidal fractures are radial and concentric. Radial fractures extend outward in a line from the point on the glass where the force originated.
Brittle materials are more likely to exhibit conchoidal fracturing. Several such materials exist in nature, such as jasper, quartz, obsidian, flint and other fine-grained materials. Conchoidal fracture is commonly observed in such materials due to their lack of a crystalline structure or cleavage.
Glass – can be naturally formed (volcanic glass called obsidian), is a solid, its chemical composition, however, is not always the same, and it does not have a crystalline structure. Thus, glass is not a mineral.
Splintery fracture is breakage into elongated fragments like splinters of wood, while hackly fracture is breakage along jagged surfaces.
Most geodes contain clear quartz crystals, while others have purple amethyst crystals. Still others can have agate, chalcedony, or jasper banding or crystals such as calcite, dolomite, celestite, etc. There is no easy way of telling what the inside of a geode holds until it is cut open or broken apart.
Calcite is the mineral component of limestone which is used primarily as construction aggregates, and in production of lime and cement.
Breccia forms where broken, angular fragments of rock or mineral debris accumulate. One of the most common locations for breccia formation is at the base of an outcrop where mechanical weathering debris accumulates. Another is in stream deposits a short distance from the outcrop or on an alluvial fan.
Chemical ClassificationSilicateStreakColorlessLusterVitreousDiaphaneityTransparent to translucentCleavagePoor cleavage, brittle with conchoidal fracture
Chert is a fine-grained sedimentary rock composed of quartz (SiO2) that is microcrystalline or cryptocrystalline quartz. It is usually organic rock but also occur inorganically as a chemical precipitate or a diagenetic replacement. It occurs as nodules, concretionary masses, and as layered deposits.
Sandstones are clastic in origin (as opposed to either organic, like chalk and coal, or chemical, like gypsum and jasper). The silicate sand grains from which they form are the product of physical and chemical weathering of bedrock.
Like all glass and some other types of naturally occurring rocks, obsidian breaks with a characteristic “conchoidal” fracture. This smooth, curved type of fracture surface occurs because of the near-absence of mineral crystals in the glass. The intersections of conchoidal fracture surfaces can be sharper than a razor.
Names: anthracite, semi-anthracite coal, bituminous coalChemical composition: carbon − 77%, ash − 6-16%Trace elements: sulfur − 0.23-1.2%, silica oxide − 2.2-5.4%, alumina − 2%, ferric oxide − 0.4%PHYSICAL PROPERTIESDensity, g/cm3: 1.3-1.8Mohs hardness: 2.2-3.8
It’s classified as an organic sedimentary rock, but rocks are combinations of minerals, and minerals are inorganic. Coal is made of decomposed plants, which are organic.
Potassium feldsparQuartzPlagioclase feldspar (same page as K-feldspar)Hornblende (an amphibole)Muscovite (a mica)Biotite (a mica; same page as muscovite)Augite (a pyroxene)Olivine
Because of the dominance of oxygen and silicon in the crust, igneous rocks are mostly made up of silicate minerals. These silicates can be generally divided into light and dark silicates. The dark silicates are also called ferromagnesian because of the presence of iron and magnesium in them.
For example, sedimentary rocks typically have grains that one can see, whereas igneous rocks don’t. Crystals in metamorphic rocks are often arranged in bands.
Mineral hardness is a key characteristic that scientists use in sample identification. Quartz is about four times harder than calcite. A piece of quartz can scratch a sample of calcite, but calcite cannot scratch quartz.
Identifying calcite is relatively easy. Firstly, it is generally light-coloured (mostly white) and is translucent to transparent. It’s hardness is about a 3 on the Moh’s hardness scale, so it can’t be scratched by your fingernail, but scratching it with a metal nail or your hammer will leave a mark.
Most minerals can be characterized and classified by their unique physical properties: hardness, luster, color, streak, specific gravity, cleavage, fracture, and tenacity.
Conchoidal fracture is helpful in identifying certain minerals and mineraloids. For instance, the mineraloid obsidian (volcanic glass) will always fracture in a conchoidal pattern. So, too, will quartz and the family of cryptocrystalline quartz minerals: chalcedony, agate, flint, chert, and jasper.
Glassy lustre, conchoidal fracture.
Direction of force determinations: This method determines which direction a projectile went through the glass by evaluating radial fractures in the glass fracture’s first concentric ring. The determination of force direction is a process easily done by a crime scene technician.
The term conchoidal is used to describe fracture with smooth, curved surfaces that resemble the interior of a seashell; it is commonly observed in quartz and glass.
Rondi: Everyone, meet Obsidian , an igneous rock that from melted rock, or magma. Obsidian is an “extrusive” rock, which means it is made from magma that erupted out of a volcano. If it was an igneous rock that formed from magma underground and did not erupt, it would have been called an “intrusive” rock.
graphite, also called plumbago or black lead, mineral consisting of carbon. Graphite has a layered structure that consists of rings of six carbon atoms arranged in widely spaced horizontal sheets.
Nickel is the fifth most abundant element on Earth. … The main mineral sources of nickel are limonite, garnierite and pentlandite. In 1848, Norway became the first large-scale nickel smelting site. Here they used a type of nickel ore known as pyrrhotite.
salt (NaCl), sodium chloride, mineral substance of great importance to human and animal health, as well as to industry. The mineral form halite, or rock salt, is sometimes called common salt to distinguish it from a class of chemical compounds called salts. table.
Conchoidal fracture breakage that resembles the concentric ripples of a mussel shell. It often occurs in amorphous or fine-grained minerals such as flint, opal or obsidian, but may also occur in crystalline minerals such as quartz.
Splintery is a fracture type that occurs in fibrous or finely acicular minerals and in minerals that have a relatively stronger structure in one direction than the other two. Chrysotile serpentine is a typical mineral with splintery fracture and kyanite is an example of a non-fibrous mineral that has this fracture.
HardnessMineralCommon Objects3CalciteCopper Penny (3+)4Fluorite5ApatiteSteel knife blade (5+), Window glass (5.5)6OrthoclaseSteel file
Typically, geodes do not have gold or diamonds in them. … Geodes are known to contain gems called Herkimer diamonds, Bristol Diamonds as well as Gold aura quartz, but they are not real gold or diamonds. Although certain quartz rock deposits have gold, it is different from the quartz crystals commonly found inside geodes.
Some people prefer using a rock saw to cut the rock in half. The rarest and most valuable geodes contain amethyst crystals and black calcite.