i was not laughing - i rather rushed to the forum to tell him it's silicon and not the ore i never laugh at someone who is wrong - it can (and actually does) happen to all of us
and actually Dave knows very well how a silicon wafer looks like - he made a very nice video showing a lot of silicon IC manufacturing stuff. and let's be realistic - the highly polished wafers with the epitaxial layer of silicon are looking way different (color, surface) than the roughly cut silicon - so no wonder if someone makes a wrong assumption (supported by incorrect wording in a letter).
and why metallic ? probably because it looks like metal and most probably because silicon is a metalloid by definition
I agree that it is bad to laugh at someones mistakes, but it I was not laughing to the fact that he was wrong, but to the suspense when he continued, and took the time to look up how silica was made into silicon, how it would be different from sand and if silica was mined in Norway.
Dave is great, I do not blame him, he should be honored that even his mistakes are amusing and attracts viewers!
I work as a researcher within material science and just because of my personal interest in the subject, I had to look up the properties of silicon. Interestingly it does not have a metallic luster/reflections, it behaves as a dielectric material with very high absorption.
For example metals does not polarize light when reflected of its surface, but glass/plastic and silicon does. Light can not penetrate metals, it is reflected if its top surface, but in silicon it can penetrate into the material (used in solar panels) and if thin enough it can go through, similarly to that of a highly colored glass object.
Wikipedia:
There is no standard definition of a metalloid, nor is there complete agreement as to which elements are appropriately classified as such.