Lime rock CaCO3(calcium carbonate) + heat --> CaCO (quicklime) + CO2
Compared to mining which was extremely dangerous and cost many a miner their limbs or even their lives, manning the kilns was relatively safe. The major mishap occurred when the kilns set fire to the wood which surrounded them.
At the published coordinates you will find some restored lime kilns. To log this cache e-mail the date the kilns were restored and also a description of the veins of lime which are present in the rocks used to build the kilns. If you have a hard time recognizing lime in its native state I recommend you do the nearby Lime Rock EarthCache.
An added note: When quicklime is heated to 2400 degrees Celsius it emits a bright glow. This limelight was used in theatrical productions before the advent of electricity.