Should I grind a window on my rock to look inside?
Only after seeking expert advice. Grinding a small window can reveal metal flecks and chondrules, but it permanently alters the specimen.
A window is a small polished area ground on the corner or edge of a stone to reveal its interior without cutting it in half. Experienced collectors and dealers sometimes do this to show the inside of a meteorite.
What it can reveal. In a chondrite, a window typically shows a grey interior with tiny shiny flecks of iron-nickel metal and, often, round chondrules. In an iron meteorite, it shows bright metal. In many Earth rocks, it reveals features such as quartz grains, bubbles or concentric layers that rule out a meteorite.
Why caution is needed. - It permanently changes the specimen, removing part of the crust and surface, which may be scientifically important. - Grinding creates dust, which should not be breathed in. - Using power tools carries risks of injury. - If the rock is a meteorite, damaging it may reduce its scientific and collector value.
Better first steps. Before grinding, look carefully at the outside, test with a magnet, check the weight and send clear photographs to a museum, university or experienced identification service. Many will say whether a window is worthwhile, or may do it themselves.
If advised to proceed. Work on a small, inconspicuous area, away from crust where possible. Use a diamond file or a grinding wheel with water to keep dust down, wear eye protection and a dust mask, and keep the piece cool.
Children should never grind or cut rocks; this is a task for adults with proper equipment.