Ordovician Calcite Brachiopod

Here are some Ordovician Period brachiopods from eastern Jefferson County, Kentucky. I picked out some that have some exposed calcite. I originally posted this as quartz but a KYANA member Charlie informed me that quartz is rare in Upper Ordovician Period fossils. After doing a scratch test with a pen knife, it showed it was not quartz. The white vinegar test proved inconclusive.