In the sentence - Plenty of silicon is found on Earth, but it remains a valuable material for the computer industry. What is the simple subject and predicate?

There are two clauses here, making this a compound sentence.

Clause 1 = Plenty of silicon is found on Earth

Clause 2 = it remains a valuable material for the computer industry.

Now can you see the simple subject and simple verb in each clause?

??

yes, but I'm not sure if the simple predicate in clause 1 is is or is found.

The simple subject of a sentence is the main noun or pronoun that the sentence is about, while the simple predicate is the main verb or verb phrase that tells what the subject is doing or being.

In the given sentence, "Plenty of silicon is found on Earth, but it remains a valuable material for the computer industry," the simple subject is "plenty of silicon," and the simple predicate is "is found and remains."

To find the simple subject, ask yourself "who or what is the sentence talking about?" In this case, the sentence is talking about "plenty of silicon."

To find the simple predicate, ask yourself "what is the action or state of being that is attributed to the subject?" In this case, the sentence states that silicon "is found" and "remains."