Final answer:
The correct eight-letter word to fill in the sentence is 'duress,' paralleling the pressure required to form metamorphic rocks. It signifies a situation of stress and is appropriate for describing a reaction to having a valuable rock stolen.
Step-by-step explanation:
You are certainly under a lot of heat and duress now that I have stolen your metamorphic rock. Filling in this eight-letter word makes sense as it conveys a state of being under a great strain or stress, which is quite similar to being under 'pressure.' Metamorphic rocks themselves are formed under conditions of extreme pressure and heat, transforming them from their original form into a new structure with different characteristics.
Understanding the characteristics of metamorphic rocks can sometimes be complex, as they can vary widely depending on their original form and the conditions they were subjected to. Reports on metamorphic rock characteristics that use clear spelling, grammar, and complete sentences, as well as include photographs and thorough descriptions of other samples, score well in academic settings.