Question 1
The mineral fluorite is commonly ________.
◦ conchoidal
◦ sheetlike
◦ octohedral
◦ cubical
Question 2
Quartz has a characteristic conchoidal fracture, yet rock shops often sell quartz as elongate six sided objects with a pointed termination. What causes this shape?
◦ The planar faces that form the object are crystal faces that grow when the crystals grew into a void.
◦ The rock shop cuts them that way with abrasives. The facets are cut to give the crystals more "power" for the crystal people.
◦ Quartz usually is amorphous, consistent with its conchoidal fracture, but when it grows it grows against minerals with planar faces, causing this shape.
◦ You should never buy a crystal like this because it is clearly fake, only artificial crystals grow this way.
Mackerel tabby, showing the characteristic "M" on its forehead.
x-ray view of a fracture
X-ray showing oblique fracture of the humerus.
Quartz
Conchoidal fracture
Rock Type Influences Weathering