"Pertinacity" Natural Recordings by Native Speakers
Pertinacity refers to the quality of persisting in a course of action in spite of difficulties, opposition, or discouragement; stubbornness.
I apologize, but I couldn't find the word "pertest" in my dictionaries or online resources. It's possible that it's a misspelling or a word that is not commonly used. Could you please provide more context or clarify the meaning you think it has? I'll do my best to help you understand it.
Perthites are a type of mineral aggregate that typically consists of small, rounded or ovoid crystals of one mineral (usually quartz) surrounded by a matrix of another mineral (usually mica). They are often found in igneous rocks, particularly in granitoid and pegmatitic rocks, and are named after their first discovery in Perthshire, Scotland.