why do some minerals like graphite feel greasy?

Question

i tried researching this and looking it up in my txtbk but they dont' really explain it. thanks a lot guys

um..okay can anyone give me a reason thats simple and short but explains more specifically than just "its properties"? kthx

Answer 1

Graphite is formed of carbon rings that are arranged like chicken wire--in flat layers. The layers can and do just slide over one another--which is what makes it feel slippery and greasy.
On the other hand, diamonds are formed of carbon interlocked in a 3D (not flat!) arrangement that is very solid. No slipping and sliding allowed.
Compare their structures here--drawings showing the difference: http://www.avogadro.co.uk/structure/chemstruc/network/g-molecular.htm

Clays (phyllosillicates) are minerals that can feel greasy too, because they are also formed of flat sheets.

Answer 2

The structure of graphite is flat and on earth it allows air between the particles so that they slip past each other. I mention on earth because it is only like that on earth. In a vacuum the air is not between the particles and cannot be utilized as a lubricant as it can on earth.
Here are the properties of graphite:
Graphite is a soft, crystalline form of carbon. Other forms are diamond and fullerenes ("buckyballs"). It is gray to black, opaque, and has a metallic luster. It is flexible but not elastic. Graphite occurs naturally in metamorphic rocks such as marble, schist, and gneiss. It exhibits the properties of a metal and a nonmetal, which make it suitable for many industrial applications. The metallic properties include thermal and electrical conductivity. The nonmetallic properties include inertness, high thermal resistance, and lubricity. Because graphite flakes slip over one another, giving it its greasy feel, graphite has long been used as a lubricant in applications where “wet” lubricants, such as oil, can not be used. Technological changes are reducing the need for this application.

Some of the major end uses of graphite are in high-temperature lubricants, brushes for electrical motors, friction materials, and battery and fuel cells.

Answer 3

It's due to their properties, wheather it's chemical or physical.

Example-Talc which is one of the softest minerals known to man due to its properties.

Answer 4

its due to their properties. So, in simple form, because God make it that way...