Gemstone Hardness. The Mohs scale of mineral hardness was created by German mineralogist, Friedrich Mohs, in 1822 to measure the relative hardness or scratch resistance of various minerals. He based it on ten readily available minerals. As it is an ordinal scale, two minerals must be compared to decide which is harder. The scale is neither linear nor logarithmic.
AMC Black tickets are exchange items that are NOT eligible toward earning AMC Stubs rewards either at time of purchase or time of redemption. Valid seven days a week. Yellow Ticket Terms and Conditions. Not Valid in: CALIFORNIA, NEW YORK, and NEW JERSEY Present at box office only.
Amex Reveals Details About Its Secretive Centurion Card. The Amex Black Card as seen in its natural habitat: by Clemson via Flickr. The American Express Centurion Card (aka the Black Card) is the Bugatti of credit cardsâfew can afford it and if you see one in public youâll probably stop and stare.