My copper sulfate crystal, about the size of a half a banana and grown from information on the article’s site, is doing well submerged in mineral oil in a seale

My copper sulfate crystal, about the size of a half a banana and grown from information on the article’s site, is doing well submerged in mineral oil in a sealed glass jar. If you do this, get it fairly dry first because surface moisture will form a thin layer between the oil and the crystal making a shiny surface from different refractive indices.