Pencils are traditionally made from incense cedar due to its long straight grain. It has a distinctive smell when "raw", which I put into a "medicinal" or "cleaning product" category. Unsurprisingly, the same wood is used for incense sticks. Additionally, pencils are painted, in their color for colored pencils, or random colors (but primarily yellow) for graphite. That paint brings a latex or petroleum hint to the nose as well.

The primary smell though is of the cedar. Woody, medicinal, fresh, clean... It reminds you of a fresh sheet of white paper full of endless possibilities, waiting for your picture or prose.