Judging quality
Grade by blue depth and pattern: deep 'volcanic blue' with clean white webbing is top grade, pale grey-blue is common. There is no other source, so provenance claims elsewhere are false.
Pectolite
Blue pectolite found in exactly one place on earth: a single mountainside in the Dominican Republic. Volcanic in origin, its patterning looks like sunlight on shallow Caribbean water.

Grade by blue depth and pattern: deep 'volcanic blue' with clean white webbing is top grade, pale grey-blue is common. There is no other source, so provenance claims elsewhere are false.
Fades in prolonged sunlight and is relatively soft. Store in the dark; clean with a damp cloth.
Known to locals for generations, it was formally identified in 1974 and named for the discoverer's daughter Larissa and the Spanish word for sea, mar.
Cultural history, recorded as tradition rather than as medical or scientific claim.
See it in person
Both rooms are open six days a week, and there is always someone happy to pull pieces out of the case so you can compare them under the light.