Qualities of a mineral that classify it as ore

Usefulness and profitability are the qualities of a mineral that classify it as an "ore".

This means that when the Geologist's who studied minerals, they classified them. It's standards in classification is meant to show elements and metals that are can profitably extracted from a rock.  

the leaf is an organ of a typical plant, and the main functions are to complete photosynthesis and allow the plant to exchange gas, just like how we have the respiratory system. leaves have the stomata, which collects maintains co2 and o2 levels. this is necessary for cell metabolism. the leaf also collects sunlight using chloroplasts. succinctly, leaves own a pivotal role in sustaining plant life.

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