Epsomite
A mineral is a naturally occurring (a man-made substance is not a mineral), usually inorganic (nonliving), homogenous solid (materials that cannot be physically subdivided into simpler chemical compounds. The requirement that a mineral must be a solid eliminates all gases and liquids). With a definite chemical composition (same basic "recipe") that is changeable within fixed limits and has a highly ordered atomic arrangement (This means that the atoms in a mineral are arranged in a regular, repeated, three-dimensional pattern).
The mineral Epsomite forms as an efflorescence (a precipitation from vapors) on limestone cave walls and in mines. It is found in deposits from hot springs and fumaroles such as on Mount Vesuvius, Italy, and in oxidized (combined with oxygen) areas of pyrite deposits. The main sources of Epsomite are Canada, Czech Republic, England, France, Germany, Italy, and South Africa. It is also found in Arizona, California, Indiana, Kentucky, Montana, Nevada, New Mexico, Tennessee, Utah, Washington, and Wyoming, United States.
Epsomite is a laxative that is commonly known as Epsom salts, it is also an ingredient of sizing- the thin, gelatinous coating put on cotton and silk to make them waterproof and to help them keep their shape. It gets it’s name from the location that it was discovered in, Epsom in Surrey, England. The mineral’s chemical formula is MgSO47H2O and it is in the Sulfate class.
Enormous crystals have been found in New Mexico and Washington, and the largest (and rarest) crystals are more than 10-ft. (3 m) long. Epsomite is more commonly found as crusts and massive collections on the surface of other minerals and rocks, and forms typically in white fibrous masses of acicular (needle-shaped) microcrystals.
In 1822, Friedrich Moh, a German mineralogist devised a crude but sensible method of comparing hardness or scratch resistance of minerals. Moh took ten well-known, easily available minerals, and arranged them in order of their "scratch hardness". If a mineral from the list can scratch a specimen, then the specimen is softer, but if the specimen scratches a mineral from the list then it is harder than that mineral. This quick and easy field test has become universally known as Moh’s scale. On the scale, Epsomite is between 2 and 2.5 in hardness.
The color of Epsomite’s surface is either colorless (picture shown below) or white with pale shades of pink and green (picture shown above). The surface color of a mineral may vary and can change, making it an unreliable method of identifying the mineral. A reliable method involving color is called streak, which is a way to find the color of a mineral’s powder. The color of the powder doesn’t vary and it is found by scraping the mineral across the surface of an unglazed piece of porcelain. This leaves a "streak" of the powder’s color across the surface of the porcelain. Epsomite has a white powder, which leaves a white streak.
A mineral’s luster is the way it reflects light from its surface, which is another type of mineral indicator. Large epsomite crystals are glassy, while most smaller specimens are silky to earthy (dull).
The way a mineral breaks apart can also help to identify it because of two types of properties: cleavage and fracture. Cleavage occurs when a mineral splits easily along flat surfaces, and fracture is when a mineral doesn’t split apart evenly, instead it breaks. When cleavage occurs in Epsomite, it breaks in three directions: perfect in one direction and distinct in two other directions. When Epsomite breaks apart unevenly (fracture) it is conchoidal, meaning that it has a curved, rough edge where it broke (it looks like ice cream after some of it has been taken out with a rounded ice cream scoop).
Another easy field test that can help to identify a mineral is called taste. The name says it all! Epsomite tastes just like epsom salt, which probably tastes like regular table salt: bitter. The mineral Epsomite is very soluble in water, which means that it can easily dissolve in water. The strange thing is that in dry air conditions, Epsomite may lose one molecule of water and convert to the very closely related mineral Hexahydrite (MgSO4-6H20).
I hope you learned a bit about Epsomite, and minerals at the same time because I sure did. This essay explained several simple field indicators for minerals and gave information on the mineral Epsomite for anyone that wants to learn about minerals.
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