It is important to distinguish this from the famous "Adagio in G Minor" often attributed to Albinoni, which was actually written by the 20th-century musicologist . The Op. 6 sonatas are part of a collection titled Trattenimenti armonici per camera (Harmonic Amusements for the Chamber), published around 1711. Sheet Music Sources
The piece you are looking for is the by the Italian Baroque composer Tomaso Albinoni . The first movement is titled "I. Grave adagio" . Sonata No. 2 in G Minor, Op. 6: I. Grave adagio
: Provides public domain scores for Albinoni's Op. 6 collection, which includes Sonata No. 2. It is important to distinguish this from the