What this green mineral could be? it's harder than glass : r

What are these green glass like crystals? : r/whatsthisrock

Quartz: Mineral information, data and localities.

Hard Water and How It Damages Plumbing

3 Minerals – An Introduction to Geology

How to Preserve Crystals

5.6 Mineral Properties – Physical Geology – H5P Edition

Reading: Physical Characteristics of Minerals

mineral ID Flashcards

I have no idea if this is glass, mineral, rock, or something else