Cement is primarily made up of calcium carbonite, commonly called calcite. This is a very common mineral with numerous forms including limestone and marble. Some of this is in crystalline form which can reflect light. There are even some calcite deposits in New Jersey that react under blacklight.
This calcite crystal mined in Tennessee is just one of a variety of crystal forms the mineral can be found in:
While a crystal of this size would probably be set aside, smaller chunks regularly end up in calcite used for making cement. After being ground and heated these crystals are evenly dispersed, making the cement sparkle.
Sidewalks and side streets are more likely to sparkle than major roads as highways are generally made out of asphalt. This compound is made out of cement covered in tar, obscuring the crystals.
Posted 4448 day ago