Is a shiny black rock a meteorite?
Usually not, because most meteorites have a dull, matt black crust, while shiny black rocks are more often obsidian, slag, hematite, magnetite or desert-varnished stones. A few meteorites, such as eucrites, do have glossy crusts.
It is a natural thought: meteorites are often described as black, so a glossy black stone feels like a good candidate. In fact, shine is more often a warning sign than a clue. The fusion crust on most meteorites, especially the common ordinary chondrites, is dull to satiny, a little like black matt paint, and very thin.
Many Earth materials are shiny and black. Obsidian is natural volcanic glass, glossy with curved, shell-shaped fractures. Slag from furnaces can have a glassy black skin, often with bubbles. The iron ores hematite and magnetite can be metallic and lustrous; hematite gives a red-brown streak on an unglazed tile, and magnetite a black one. In deserts, ordinary rocks can acquire desert varnish, a dark shiny coating of clay and iron and manganese oxides built up over a long time. In Britain, black-skinned flint and polished river pebbles are frequent visitors to identification desks.
There are honest exceptions. Some achondrites, meteorites that melted on their parent body, form a glossy crust because their melted surface turns to glass. Eucrites from the asteroid Vesta are the best-known example; well-preserved pieces of Millbillillie, which fell in Western Australia in 1960, and Stannern, which fell in what is now the Czech Republic in 1808, have a lovely shiny black skin. Even then, a chip reveals a paler grey interior, and the crust is less than about a millimetre thick.
So, look beyond the shine. Check whether the dark layer is only a thin skin, whether the inside differs, and whether there are bubbles or glassy breaks. If you are still curious, ask a museum or university geology department rather than testing with acid or heat.