Although silicone is made from a natural source, it is a man-made, synthetic material. Silicone is derived from sand, and to make it, quartz sand is heated at temperatures of up to 1800℃ (3272℉). After that, the materials comes through several more steps which involve mixing it with other chemicals and adding water. Overall, the production processes is energy-intensive and requires the usage of many chemicals. That means, it is not sustainable.  

Silicone is versatile as it can be made into different consistencies, such as to become a gel, rubbery in texture, or hard like a rock. 

Silicone is not the most environmentally friendly material. Producing silicone uses hydrocarbons derived from petroleum, which is not sustainable. It is difficult to recycle, and most facilities will not accept it. 

Silicone is not biodegradable.  

Methods for recycling silicone have been patented since 1991, but involve highly toxic chemicals like sulfuric acid heated to high temperatures, and result in waste products that must be disposed of in landfills. 

Silicone is a stable material with high resistance to extreme temperatures, it does not break apart easily and it is durable. Another good thing is that it will not shed microplastics over time unlike plastics.