|
In the late 1800s this material that naturally splits into thin sheets was very popular for roofs in the northeast |
slate
|
$1,000 |
J |
ROCKS & MINERALS |
2018-06-22 |
#7790 |
|
A shade of gray is named for this rock originally used in blackboards |
slate
|
$800 |
J |
ROCKS & MINERALS |
2014-10-22 |
#6923 |
|
This blackboard rock is formed when shale is subjected to immense heat & pressure |
slate
|
$800 |
J |
ROCKS & MINERALS |
2007-12-25 |
#5362 |
|
This metamorphic rock for which a shade of gray is named is abundant in Wales |
slate
|
$800 |
DJ |
ROCKS & MINERALS |
1993-06-24 |
#2044 |
|
Shale changes into this rock metamorphically & also by changing 2 letters |
slate
|
$1,000 |
DJ |
ROCKS & MINERALS |
1993-05-14 |
#2015 |
|
This dark gray stone is used to make blackboards & billiard tabletops |
slate
|
$400 |
DJ |
ROCKS & MINERALS |
1992-10-23 |
#1870 |
|
Metamorphism turns limestone into marble & shale into this |
slate
|
$600 |
DJ |
ROCKS & MINERALS |
1991-02-18 |
#1496 |
|
Intense pressure on shale turns it into this "blackboard" material |
slate
|
$200 |
DJ |
GEOLOGY |
1986-05-15 |
#439 |