This is a well formed crystal of SPHALERITE.
To see more pictures and information, following the link from the mineral name.
Yellow SULFUR crystals from Mexico.
TALC comes in a variety of colors and normally feels
"soapy". The soapy feel is the result of microscopic crystals
that are cleaving on your hand.
TOURMALINE also occurs in a variety of
colors. Most commonly it is black. Colored varieties are used as
gemstones.
TURQUOISE is always some shade of blue or
blue-green. (You will not see this mineral on the Quiz.)
