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? a. quartz usually is amorphous, consistent with its conchoidal fracture, but when it grows it grows against minerals with planar faces, causing this shape. b. the rock shop cuts them that way with abrasives. the facets are cut to give the crystals more "power" for the crystal people. c. the planar faces that form the object are crystal faces that grow when the crystals grew into a void. d. you should never buy a crystal like this because it is clearly fake, only artificial crystals grow this way.

C. The planar faces that form the object are crystal faces that grow when the crystals grew into a void.

Explanation:

Quartz is considered the most abundant mineral on earth. Its best known form is quartz crystals, similar to broken glass pieces. Quartz formations are part of a geological process that can take thousands of years. Quartz stones are mainly composed of Silicon Dioxide (SiO2), being present in all types of rock formations on the planet, whether igneous, metamorphic or sedimentary. Quartz is sold as six-sided elongated objects with a sharp end, this shape is caused because the flat faces that form the object are crystal faces that grow when crystals grow in a void.

cramming before a final is bad because it makes a student's stress level higher. students who embrace cramming to get through a final exam week find themselves struggling to perform consistently, once the brain adjusts to prolonged sleep deprivation.

complete the square on the right side of the equation;

-5(x + 0)^2 + 15

answer: d. y = -x^2 + 15