Chalcedony is a microcrystalline type of quartz, the form of Quartz that is compact and formed of microscopic crystals. It occurs in many different forms, including stalactites & stalagmites. 
 
Stalactites usually grow when silica rich waters drop their dissolved minerals when encountering changes in environmental and chemical conditions.
 
A stalactite is a type of formation that hangs from the ceiling of caves, hot springs, or even structures such as bridges and mines.
 
A stalagmite is a formation that occurs when stalactite drip to the ground, creating columns, rising from the floor of a cave. They often unite with the stalactite.
 
Easy to know the difference by remembering a stalactite holds 'tight' to the ceiling and a stalagmite grows 'mighty' from the ground.
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Cave formations take millions of years to form.
 
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* Photos show all sides.
* Sizes, shapes and colors my vary due to being a natural stone, being hand-carved and/or difference in computer monitors.