Popular "hashish" found in the UK.

soap bars weighing 9oz / 250 grams, on average contain 1/3 oz / 10 grams of flower / resin and up to 200 grams of inert ground-up shade leaf. The remainder consist of c.40 grams of various noxious substances. Using mass spectrometry they found the most common of these are as follows:
Glue
Dyes
Carcinogenic solvents such as Toluene and Benzene (from petrol/turpentine/diesel)
Henna
Pine resin (to mask the smell of the above)
Plastic (often from repressing/remixing bars using petrol/diesel)
Tranquilizers / barbiturates (often veterinary in origin like ketamine)
Other ingredients found include;
Tar / bitumen
Wax / Boot polish
Condensed milk powder
Brick dust / sand
Digested organic matter / excrement