Clues for: Minerals

Question Answer Value Airdate
3-letter term for the rocks mined for aluminum, iron or lead among others ore 100 May 23, 1988
Of a stalagmite, a stalactite or a helictite, the one that only grows from the ground up stalagmite 200 May 23, 1988
Pyrite contains both sulfur & iron but only a "fool" thinks it contains this gold 300 May 23, 1988
From Greek for "to write", it's what does the writing in most pencils graphite 400 May 23, 1988
The hardness of a mineral is measured by this scale Mohs 500 May 23, 1988
You’ll discover not gold, but a black mark, after rubbing this “gold” on porcelain fool’s gold 100 April 22, 1986
A scratch test won’t reveal a mineral’s allergies, but this property hardness 200 April 22, 1986