Talc
What is a Mineral?
Not all minerals are perfect and shiny, as a matter of a fact most of them look like rocks but they aren’t. So you may be asking, what’s the difference between a rock and a mineral? Well there are four questions you must answer to tell if something is a mineral. First, Does it have a crystalline structure? Basically this means that it has a repeating inner structure that often reflects the shape of a crystal. Then, Is it a solid? Minerals can not be either a liquid or a gas only solid. Is it formed it nature? Man- made minerals are not minerals. Is it in organic? Meaning it is not made of living things. If you answered yes to all of these questions it is a mineral.
History of Talc
Talc was first discovered by a geologist in 1546. The name talc comes form the Arabic language but is also known by several other names such as steatite, soapstone, potstone and French chalk. It is believed by geologists that Talc is formed over millions of years, cave men 15,000 years ago used it as an ingredient in their paints and it is also believed that back in the times of the tang dynasty it was used in glazed pottery.
Mohs Hardness Scale
Mohs hardness scale is a scale that identifies the hardness of a mineral. It rates the mineral’s hardness from one to ten, ten being the hardest.
A minerals rating on the hardness scale is determined by a scratch test. For example the diamond is the hardest mineral because no other mineral on the scale is able to scratch it. Basically if two minerals can both scratch each other they are of the same hardness but if one can only scratch the other that one will be higher on the scale. Since Fluorite is a 4 on the scale it means that fluorite can scratch all the minerals below it but not be scratched by them. Also if a penny can scratch a mineral it rates a 3, a fingernail is 2.5, knife blade 5.5, glass 5.5 and steel file 6.5. Talc rates a one on the scale meaning that it is the softest mineral and can be scratched by just about anything.
Who is Moh? The Mohs hardness scale was name after Friedrich Moh, a German mineralogist of the seventeenth century. In 1822 he this method of mineral hardness and scratch resistance.
Color
Talc is usually white to a pale of dark green color, gray or even brown. If the specimen is impure meaning that something has caused a chemical reaction with inside it the mineral can turn bright red or pink. The color is not the best way to identify a mineral because it can be changed by weathering and is not an accurate source of information.
Streak
The fine powder or mark made by a mineral when scratched or rubbed against a harder surface. The streak of a mineral is the color of the mineral in powder form. This can be determined by dragging the mineral across an unpolished tile. The color of a mineral's streak can not be changed; weathering has no effect on the streak. Talc has a white streak no matter what color it is on the out side.
Luster
Luster is the way the surface of a mineral reflects light. There are three different ways to classify a minerals luster. Metallic is when a mineral is very shiny, non-metallic is when the mineral is kind of dull and does shine at all. Right in between the tow you have sub-metallic, which shines a little bit but is still dull. The mineral talc has a non metallic luster, it is often described a pearly of greasy
Cleavage/Fracture
Cleavage is the splitting along the definite crystalline structure creating smooth surfaces, fracture is the tendency a mineral has to break along flat surfaces. Talc has a perfect cleavage and fracture because it is so soft that it breaks so easily. Notice in the picture above the little cracks in the mineral show how easily it chips off.
Density
The formula for density is D=M/V. What this basically means is that you Find the Mass using a triple beam balance and divide it by the volume using a graduated cylinder. The mass is measured in grams. The volume is measured in ML, a good tip to use when measuring volume is to first fill it up to the 100ML mark then drop the mineral in. Once you get an accurate reading subtract 100ML from that to give you the minerals volume. Talc’s volume is 2.82.
Talc can be used in different cosmetic products and in the process of making pottery when ground up into a powder but it uses are constantly expanding.