Historical clue formulations

• Volcanic gems found on every continent — 2026-06-14
• Striped stones — 2025-06-08
• Banded gemstones — 2024-04-17
• Colorful banded rocks — 2023-11-27
• Banded stones — 2019-02-07
• Shooting marbles — 2016-03-30
• Swirly-colored marbles — 2015-07-30
• Banded gemstones — 2014-04-09
• Playing marbles — 2013-04-08
• Some marbles — 2012-06-04
• Banded marbles — 2012-01-17
• Swirly marbles — 2012-01-01
• Ancient May birthstones — 2011-10-30
• Striped stones — 2011-02-27
• Playing marbles — 2010-11-15
• Balls with bands — 2010-07-10
• Cat's-eye relatives — 2010-02-19
• Playing marbles — 2009-07-15
• Semiprecious stones — 2008-10-01
• They're seen at marble tournaments — 2007-09-03
• Playing marbles — 2006-01-23
• Small types — 2004-12-12
• Playing marbles — 2003-06-03
• Some marbles — 2002-05-13
• Playing marbles — 2001-06-26
• They're used in classified ads — 2001-02-24
• Glass marbles — 1999-09-13
• Playing marbles — 1999-06-06
• Playing marbles — 1997-05-14
• Certain marbles — 1997-04-14
• Marbles — 1997-02-09
• Playing marbles — 1995-12-25
• Migs' relatives — 1995-03-19
• Some chalcedonies — 1994-11-17