As with current margin rules, all short sales must be done in a margin account. If you sell short and then buy to cover on the same day, it is considered a day trade. Does the rule apply to day-trading options? Yes. The day-trading margin rule applies to day trading in any security, including options. What is a pattern day trader?
This is completely normal and is seen on $300+ Benchmade custom balisongs (tang pins deform or pivot screws back out). On a balisong with screw construction, LocTite is used to hold the pins in place. On FHMs, I use industrial strength epoxy.
Aragonite is orthorhombic, vaterite is hexagonal and calcite is trigonal. Aragonite is a common mineral, but is vastly out distanced by calcite which is the more stable mineral at most temperatures and pressures and in most environments. Vaterite on the other hand is extremely scarce and rarely seen.