Based on your description, there are several possibilities for the type of mineral or rock you have found. However, without a physical examination or a more detailed analysis, it's challenging to provide a precise identification. Here are a few educated guesses based on the characteristics you've described:
1. Meteorite:The density, metallic sound, and vitrified exterior could suggest a meteorite. Meteorites are often denser than ordinary rocks and can have a fusion crust (vitrified exterior) formed as they pass through the atmosphere. However, most meteorites are magnetic due to their iron content, which doesn't align with your observation.
2. Hematite or Magnetite: These are dense minerals, and hematite can be non-magnetic. However, both typically leave a streak (red for hematite, black for magnetite), which contradicts your observation.
3. Basalt or Volcanic Glass (Obsidian): If the rocks are primarily composed of dark-colored silica and have a vitrified appearance, they might be a form of basalt or volcanic glass. Basalt is a dense, dark-colored igneous rock, and obsidian is naturally occurring volcanic glass, which can appear vitrified.
4. Industrial Slag: Mentioned by
@Johnho, Slag is a by-product of metal smelting and can look similar to natural rocks. It's often dense, can be non-magnetic, and might have a glassy or vitrified exterior.
5. Anthracite Coal: This is a form of hard coal that's not magnetic and is very dense. It doesn't leave a streak like softer coals, but it's less likely to sound metallic.
Given that a local university professor was unable to identify the material, you might consider reaching out to a geology department at a university with a stronger focus on mineralogy or to a state geological survey. Additionally, some museums offer identification services. You can also contact a professional geologist or a mineralogist for a more detailed analysis.
Remember, accurate identification often requires not just visual inspection but also tests like hardness, specific gravity, and perhaps even a chemical assay or x-ray diffraction analysis.